diff --git a/src/corelib/tools/qline.cpp b/src/corelib/tools/qline.cpp
index dc0a6c72fb6..f90dc1785a9 100644
--- a/src/corelib/tools/qline.cpp
+++ b/src/corelib/tools/qline.cpp
@@ -322,7 +322,7 @@ QDataStream &operator>>(QDataStream &stream, QLine &line)
     A QLineF describes a finite length line (or line segment) on a
     two-dimensional surface. QLineF defines the start and end points
     of the line using floating point accuracy for coordinates.  Use
-    the toLine() function to retrieve an integer based copy of this
+    the toLine() function to retrieve an integer-based copy of this
     line.
 
     \table
@@ -458,7 +458,7 @@ QDataStream &operator>>(QDataStream &stream, QLine &line)
 /*!
     \fn QLine QLineF::toLine() const
 
-    Returns an integer based copy of this line.
+    Returns an integer-based copy of this line.
 
     Note that the returned line's start and end points are rounded to
     the nearest integer.
@@ -516,12 +516,9 @@ QDataStream &operator>>(QDataStream &stream, QLine &line)
 /*!
     \fn void QLineF::setLength(qreal length)
 
-    Sets the length of the line to the given \a length. QLineF will
-    move the end point - p2() - of the line to give the line its new
-    length, unless length() was previously zero, in which case no
-    scaling is attempted. For lines with very short lengths
-    (represented by denormal floating-point values), results may be
-    imprecise.
+    Sets the length of the line to the given finite \a length. QLineF will move
+    the end point - p2() - of the line to give the line its new length, unless
+    length() was previously zero, in which case no scaling is attempted.
 
     \sa length(), unitVector()
 */
@@ -558,9 +555,8 @@ QDataStream &operator>>(QDataStream &stream, QLine &line)
 /*!
   \fn qreal QLineF::pointAt(qreal t) const
 
-  Returns the point at the parameterized position specified by \a
-  t. The function returns the line's start point if t = 0, and its end
-  point if t = 1.
+  Returns the point at the position specified by finite parameter \a t. The
+  function returns the line's start point if t = 0, and its end point if t = 1.
 
   \sa dx(), dy()
 */
diff --git a/src/corelib/tools/qline.h b/src/corelib/tools/qline.h
index 9b544f2e7ed..426d69cd6d4 100644
--- a/src/corelib/tools/qline.h
+++ b/src/corelib/tools/qline.h
@@ -372,7 +372,9 @@ constexpr inline QPointF QLineF::center() const
 
 inline void QLineF::setLength(qreal len)
 {
+    Q_ASSERT(qIsFinite(len));
     const qreal oldLength = length();
+    Q_ASSERT(qIsFinite(oldLength));
     // Scale len by dx() / length() and dy() / length(), two O(1) quantities,
     // rather than scaling dx() and dy() by len / length(), which might overflow.
     if (oldLength > 0)
diff --git a/src/corelib/tools/qmargins.cpp b/src/corelib/tools/qmargins.cpp
index 5b3c04d11e2..38a56fa513a 100644
--- a/src/corelib/tools/qmargins.cpp
+++ b/src/corelib/tools/qmargins.cpp
@@ -52,7 +52,7 @@ QT_BEGIN_NAMESPACE
 
     \brief The QMargins class defines the four margins of a rectangle.
 
-    QMargin defines a set of four margins; left, top, right and bottom,
+    QMargin defines a set of four margins; left, top, right, and bottom,
     that describe the size of the borders surrounding a rectangle.
 
     The isNull() function returns \c true only if all margins are set to zero.
@@ -76,7 +76,7 @@ QT_BEGIN_NAMESPACE
 /*!
     \fn QMargins::QMargins(int left, int top, int right, int bottom)
 
-    Constructs margins with the given \a left, \a top, \a right, \a bottom
+    Constructs margins with the given \a left, \a top, \a right, and \a bottom
 
     \sa setLeft(), setRight(), setTop(), setBottom()
 */
@@ -467,8 +467,8 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
 
     \brief The QMarginsF class defines the four margins of a rectangle.
 
-    QMarginsF defines a set of four margins; left, top, right and bottom,
-    that describe the size of the borders surrounding a rectangle.
+    QMarginsF defines a set of four margins; left, top, right, and bottom,
+    that describe the finite size of the borders surrounding a rectangle.
 
     The isNull() function returns \c true only if all margins are very close to zero.
 
@@ -491,7 +491,8 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
 /*!
     \fn QMarginsF::QMarginsF(qreal left, qreal top, qreal right, qreal bottom)
 
-    Constructs margins with the given \a left, \a top, \a right, \a bottom
+    Constructs margins with the given \a left, \a top, \a right, and \a bottom.
+    All parameters must be finite.
 
     \sa setLeft(), setRight(), setTop(), setBottom()
 */
@@ -542,27 +543,27 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
 
 
 /*!
-    \fn void QMarginsF::setLeft(qreal left)
+    \fn void QMarginsF::setLeft(qreal aleft)
 
-    Sets the left margin to \a left.
+    Sets the left margin to \a aleft (which must be finite).
 */
 
 /*!
-    \fn void QMarginsF::setTop(qreal Top)
+    \fn void QMarginsF::setTop(qreal atop)
 
-    Sets the Top margin to \a Top.
+    Sets the top margin to \a atop (which must be finite).
 */
 
 /*!
-    \fn void QMarginsF::setRight(qreal right)
+    \fn void QMarginsF::setRight(qreal aright)
 
-    Sets the right margin to \a right.
+    Sets the right margin to \a aright (which must be finite).
 */
 
 /*!
-    \fn void QMarginsF::setBottom(qreal bottom)
+    \fn void QMarginsF::setBottom(qreal abottom)
 
-    Sets the bottom margin to \a bottom.
+    Sets the bottom margin to \a abottom (which must be finite).
 */
 
 /*!
@@ -613,8 +614,8 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
     \fn const QMarginsF operator+(const QMarginsF &lhs, qreal rhs)
     \relates QMarginsF
 
-    Returns a QMarginsF object that is formed by adding \a rhs to
-    \a lhs.
+    Returns a QMarginsF object that is formed by adding \a rhs (which must be
+    finite) to each component of \a lhs.
 
     \sa QMarginsF::operator+=(), QMarginsF::operator-=()
 */
@@ -623,8 +624,8 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
     \fn const QMarginsF operator+(qreal lhs, const QMarginsF &rhs)
     \relates QMarginsF
 
-    Returns a QMarginsF object that is formed by adding \a lhs to
-    \a rhs.
+    Returns a QMarginsF object that is formed by adding \a lhs (which must be
+    finite) to each component of \a rhs.
 
     \sa QMarginsF::operator+=(), QMarginsF::operator-=()
 */
@@ -633,8 +634,8 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
     \fn const QMarginsF operator-(const QMarginsF &lhs, qreal rhs)
     \relates QMarginsF
 
-    Returns a QMarginsF object that is formed by subtracting \a rhs from
-    \a lhs.
+    Returns a QMarginsF object that is formed by subtracting \a rhs (which must
+    be finite) from each component of \a lhs.
 
     \sa QMarginsF::operator+=(), QMarginsF::operator-=()
 */
@@ -645,7 +646,7 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
     \overload
 
     Returns a QMarginsF object that is formed by multiplying each component
-    of the given \a lhs margins by \a rhs factor.
+    of the given \a lhs margins by finite factor \a rhs.
 
     \sa QMarginsF::operator*=(), QMarginsF::operator/=()
 */
@@ -656,7 +657,7 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
     \overload
 
     Returns a QMarginsF object that is formed by multiplying each component
-    of the given \a lhs margins by \a rhs factor.
+    of the given \a lhs margins by finite factor \a rhs.
 
     \sa QMarginsF::operator*=(), QMarginsF::operator/=()
 */
@@ -669,6 +670,8 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
     Returns a QMarginsF object that is formed by dividing the components of
     the given \a lhs margins by the given \a rhs divisor.
 
+    The \a divisor must not be either zero or NaN.
+
     \sa QMarginsF::operator*=(), QMarginsF::operator/=()
 */
 
@@ -721,7 +724,7 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
     \fn QMarginsF &QMarginsF::operator+=(qreal addend)
     \overload
 
-    Adds the \a addend to each component of this object
+    Adds the given finite \a addend to each component of this object
     and returns a reference to it.
 
     \sa operator-=()
@@ -731,7 +734,7 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
     \fn QMarginsF &QMarginsF::operator-=(qreal subtrahend)
     \overload
 
-    Subtracts the \a subtrahend from each component of this object
+    Subtracts the given finite \a subtrahend from each component of this object
     and returns a reference to it.
 
     \sa operator+=()
@@ -740,8 +743,8 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
 /*!
     \fn QMarginsF &QMarginsF::operator*=(qreal factor)
 
-    Multiplies each component of this object by \a factor
-    and returns a reference to it.
+    Multiplies each component of this object by the given finite \a factor
+    and returns a reference to this object.
 
     \sa operator/=()
 */
@@ -749,8 +752,10 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
 /*!
     \fn QMarginsF &QMarginsF::operator/=(qreal divisor)
 
-    Divides each component of this object by \a divisor
-    and returns a reference to it.
+    Divides each component of this object by \a divisor and returns a reference
+    to this object.
+
+    The \a divisor must not be either zero or NaN.
 
     \sa operator*=()
 */
@@ -758,7 +763,7 @@ QDebug operator<<(QDebug dbg, const QMargins &m)
 /*!
     \fn QMargins QMarginsF::toMargins() const
 
-    Returns an integer based copy of this margins object.
+    Returns an integer-based copy of this margins object.
 
     Note that the components in the returned margins will be rounded to
     the nearest integer.
diff --git a/src/corelib/tools/qmargins.h b/src/corelib/tools/qmargins.h
index d947e2da8ed..cf40b89ee0a 100644
--- a/src/corelib/tools/qmargins.h
+++ b/src/corelib/tools/qmargins.h
@@ -311,10 +311,10 @@ public:
     constexpr qreal right() const noexcept;
     constexpr qreal bottom() const noexcept;
 
-    constexpr void setLeft(qreal left) noexcept;
-    constexpr void setTop(qreal top) noexcept;
-    constexpr void setRight(qreal right) noexcept;
-    constexpr void setBottom(qreal bottom) noexcept;
+    constexpr void setLeft(qreal aleft) noexcept;
+    constexpr void setTop(qreal atop) noexcept;
+    constexpr void setRight(qreal aright) noexcept;
+    constexpr void setBottom(qreal abottom) noexcept;
 
     constexpr QMarginsF &operator+=(const QMarginsF &margins) noexcept;
     constexpr QMarginsF &operator-=(const QMarginsF &margins) noexcept;
@@ -457,6 +457,7 @@ constexpr inline QMarginsF operator*(qreal lhs, const QMarginsF &rhs) noexcept
 
 constexpr inline QMarginsF operator/(const QMarginsF &lhs, qreal divisor)
 {
+    Q_ASSERT(divisor < 0 || divisor > 0);
     return QMarginsF(lhs.left() / divisor, lhs.top() / divisor,
                      lhs.right() / divisor, lhs.bottom() / divisor);
 }
diff --git a/src/corelib/tools/qpoint.cpp b/src/corelib/tools/qpoint.cpp
index 942ae995d50..80599a4caa5 100644
--- a/src/corelib/tools/qpoint.cpp
+++ b/src/corelib/tools/qpoint.cpp
@@ -495,7 +495,7 @@ size_t qHash(QPoint key, size_t seed) noexcept
 
     A point is specified by a x coordinate and an y coordinate which
     can be accessed using the x() and y() functions. The coordinates
-    of the point are specified using floating point numbers for
+    of the point are specified using finite floating point numbers for
     accuracy. The isNull() function returns \c true if both x and y are
     set to 0.0. The coordinates can be set (or altered) using the setX()
     and setY() functions, or alternatively the rx() and ry() functions which
@@ -581,7 +581,7 @@ size_t qHash(QPoint key, size_t seed) noexcept
 /*!
     \fn void QPointF::setX(qreal x)
 
-    Sets the x coordinate of this point to the given \a x coordinate.
+    Sets the x coordinate of this point to the given finite \a x coordinate.
 
     \sa x(), setY()
 */
@@ -589,7 +589,7 @@ size_t qHash(QPoint key, size_t seed) noexcept
 /*!
     \fn void QPointF::setY(qreal y)
 
-    Sets the y coordinate of this point to the given \a y coordinate.
+    Sets the y coordinate of this point to the given finite \a y coordinate.
 
     \sa y(), setX()
 */
@@ -655,7 +655,7 @@ size_t qHash(QPoint key, size_t seed) noexcept
 /*!
     \fn QPointF& QPointF::operator*=(qreal factor)
 
-    Multiplies this point's coordinates by the given \a factor, and
+    Multiplies this point's coordinates by the given finite \a factor, and
     returns a reference to this point. For example:
 
     \snippet code/src_corelib_tools_qpoint.cpp 14
@@ -671,6 +671,8 @@ size_t qHash(QPoint key, size_t seed) noexcept
 
     \snippet code/src_corelib_tools_qpoint.cpp 15
 
+    The \a divisor must not be zero or NaN.
+
     \sa operator*=()
 */
 
@@ -695,7 +697,7 @@ size_t qHash(QPoint key, size_t seed) noexcept
 /*!
     \fn QPointF QPointF::operator*(const QPointF &point, qreal factor)
 
-    Returns a copy of the given \a point,  multiplied by the given \a factor.
+    Returns a copy of the given \a point, multiplied by the given finite \a factor.
 
     \sa QPointF::operator*=()
 */
@@ -705,7 +707,7 @@ size_t qHash(QPoint key, size_t seed) noexcept
 
     \overload
 
-    Returns a copy of the given \a point, multiplied by the given \a factor.
+    Returns a copy of the given \a point, multiplied by the given finite \a factor.
 */
 
 /*!
@@ -720,7 +722,7 @@ size_t qHash(QPoint key, size_t seed) noexcept
     \overload
 
     Returns a QPointF object that is formed by changing the sign of
-    both components of the given \a point.
+    each component of the given \a point.
 
     Equivalent to \c {QPointF(0,0) - point}.
 */
@@ -728,9 +730,11 @@ size_t qHash(QPoint key, size_t seed) noexcept
 /*!
     \fn QPointF QPointF::operator/(const QPointF &point, qreal divisor)
 
-    Returns the QPointF object formed by dividing both components of
+    Returns the QPointF object formed by dividing each component of
     the given \a point by the given \a divisor.
 
+    The \a divisor must not be zero or NaN.
+
     \sa QPointF::operator/=()
 */
 
diff --git a/src/corelib/tools/qpoint.h b/src/corelib/tools/qpoint.h
index 118d837d69d..b886ce38016 100644
--- a/src/corelib/tools/qpoint.h
+++ b/src/corelib/tools/qpoint.h
@@ -295,7 +295,10 @@ public:
     friend constexpr inline QPointF operator-(const QPointF &p)
     { return QPointF(-p.xp, -p.yp); }
     friend constexpr inline QPointF operator/(const QPointF &p, qreal divisor)
-    { return QPointF(p.xp / divisor, p.yp / divisor); }
+    {
+        Q_ASSERT(divisor < 0 || divisor > 0);
+        return QPointF(p.xp / divisor, p.yp / divisor);
+    }
 
     constexpr QPoint toPoint() const;
 
@@ -406,6 +409,7 @@ constexpr inline QPointF &QPointF::operator*=(qreal c)
 
 constexpr inline QPointF &QPointF::operator/=(qreal divisor)
 {
+    Q_ASSERT(divisor > 0 || divisor < 0);
     xp /= divisor;
     yp /= divisor;
     return *this;
diff --git a/src/corelib/tools/qrect.cpp b/src/corelib/tools/qrect.cpp
index d38e532efea..64ccdb20ffb 100644
--- a/src/corelib/tools/qrect.cpp
+++ b/src/corelib/tools/qrect.cpp
@@ -1303,8 +1303,8 @@ QDebug operator<<(QDebug dbg, const QRect &r)
     \ingroup painting
     \reentrant
 
-    \brief The QRectF class defines a rectangle in the plane using floating
-    point precision.
+    \brief The QRectF class defines a finite rectangle in the plane using
+    floating point precision.
 
     A rectangle is normally expressed as a top-left corner and a
     size.  The size (width and height) of a QRectF is always equivalent
@@ -1469,8 +1469,8 @@ QDebug operator<<(QDebug dbg, const QRect &r)
 /*!
     \fn QRectF::QRectF(qreal x, qreal y, qreal width, qreal height)
 
-    Constructs a rectangle with (\a x, \a y) as its top-left corner
-    and the given \a width and \a height.
+    Constructs a rectangle with (\a x, \a y) as its top-left corner and the
+    given \a width and \a height. All parameters must be finite.
 
     \sa setRect()
 */
@@ -1569,7 +1569,7 @@ QRectF QRectF::normalized() const noexcept
 /*!
     \fn void QRectF::setLeft(qreal x)
 
-    Sets the left edge of the rectangle to the given \a x
+    Sets the left edge of the rectangle to the given finite \a x
     coordinate. May change the width, but will never change the right
     edge of the rectangle.
 
@@ -1581,7 +1581,7 @@ QRectF QRectF::normalized() const noexcept
 /*!
     \fn void QRectF::setTop(qreal y)
 
-    Sets the top edge of the rectangle to the given \a y coordinate. May
+    Sets the top edge of the rectangle to the given finite \a y coordinate. May
     change the height, but will never change the bottom edge of the
     rectangle.
 
@@ -1593,7 +1593,7 @@ QRectF QRectF::normalized() const noexcept
 /*!
     \fn void QRectF::setRight(qreal x)
 
-    Sets the right edge of the rectangle to the given \a x
+    Sets the right edge of the rectangle to the given finite \a x
     coordinate. May change the width, but will never change the left
     edge of the rectangle.
 
@@ -1603,7 +1603,7 @@ QRectF QRectF::normalized() const noexcept
 /*!
     \fn void QRectF::setBottom(qreal y)
 
-    Sets the bottom edge of the rectangle to the given \a y
+    Sets the bottom edge of the rectangle to the given finite \a y
     coordinate. May change the height, but will never change the top
     edge of the rectangle.
 
@@ -1613,7 +1613,7 @@ QRectF QRectF::normalized() const noexcept
 /*!
     \fn void QRectF::setX(qreal x)
 
-    Sets the left edge of the rectangle to the given \a x
+    Sets the left edge of the rectangle to the given finite \a x
     coordinate. May change the width, but will never change the right
     edge of the rectangle.
 
@@ -1625,7 +1625,7 @@ QRectF QRectF::normalized() const noexcept
 /*!
     \fn void QRectF::setY(qreal y)
 
-    Sets the top edge of the rectangle to the given \a y
+    Sets the top edge of the rectangle to the given finite \a y
     coordinate. May change the height, but will never change the
     bottom edge of the rectangle.
 
@@ -1707,7 +1707,7 @@ QRectF QRectF::normalized() const noexcept
     \fn void QRectF::moveLeft(qreal x)
 
     Moves the rectangle horizontally, leaving the rectangle's left
-    edge at the given \a x coordinate. The rectangle's size is
+    edge at the given finite \a x coordinate. The rectangle's size is
     unchanged.
 
     \sa left(), setLeft(), moveRight()
@@ -1717,7 +1717,7 @@ QRectF QRectF::normalized() const noexcept
     \fn void QRectF::moveTop(qreal y)
 
     Moves the rectangle vertically, leaving the rectangle's top line
-    at the given \a y coordinate. The rectangle's size is unchanged.
+    at the given finite \a y coordinate. The rectangle's size is unchanged.
 
     \sa top(), setTop(), moveBottom()
 */
@@ -1727,7 +1727,7 @@ QRectF QRectF::normalized() const noexcept
     \fn void QRectF::moveRight(qreal x)
 
     Moves the rectangle horizontally, leaving the rectangle's right
-    edge at the given \a x coordinate. The rectangle's size is
+    edge at the given finite \a x coordinate. The rectangle's size is
     unchanged.
 
     \sa right(), setRight(), moveLeft()
@@ -1738,7 +1738,7 @@ QRectF QRectF::normalized() const noexcept
     \fn void QRectF::moveBottom(qreal y)
 
     Moves the rectangle vertically, leaving the rectangle's bottom
-    edge at the given \a y coordinate. The rectangle's size is
+    edge at the given finite \a y coordinate. The rectangle's size is
     unchanged.
 
     \sa bottom(), setBottom(), moveTop()
@@ -1788,8 +1788,8 @@ QRectF QRectF::normalized() const noexcept
 /*!
     \fn void QRectF::moveTo(qreal x, qreal y)
 
-    Moves the rectangle, leaving the top-left corner at the given
-    position (\a x, \a y). The rectangle's size is unchanged.
+    Moves the rectangle, leaving the top-left corner at the given position (\a
+    x, \a y). The rectangle's size is unchanged. Both parameters must be finite.
 
     \sa translate(), moveTopLeft()
 */
@@ -1807,7 +1807,7 @@ QRectF QRectF::normalized() const noexcept
 
     Moves the rectangle \a dx along the x-axis and \a dy along the y-axis,
     relative to the current position. Positive values move the rectangle to the
-    right and downwards.
+    right and downwards. Both parameters must be finite.
 
     \sa moveTopLeft(), moveTo(), translated()
 */
@@ -1829,7 +1829,7 @@ QRectF QRectF::normalized() const noexcept
     Returns a copy of the rectangle that is translated \a dx along the
     x axis and \a dy along the y axis, relative to the current
     position. Positive values move the rectangle to the right and
-    down.
+    down. Both parameters must be finite.
 
     \sa translate()
 */
@@ -1860,8 +1860,8 @@ QRectF QRectF::normalized() const noexcept
 /*!
     \fn void QRectF::setRect(qreal x, qreal y, qreal width, qreal height)
 
-    Sets the coordinates of the rectangle's top-left corner to (\a x,
-    \a y), and its size to the given \a width and \a height.
+    Sets the coordinates of the rectangle's top-left corner to (\a x, \a y), and
+    its size to the given \a width and \a height. All parameters must be finite.
 
     \sa getRect(), setCoords()
 */
@@ -1872,7 +1872,7 @@ QRectF QRectF::normalized() const noexcept
 
     Sets the coordinates of the rectangle's top-left corner to (\a x1,
     \a y1), and the coordinates of its bottom-right corner to (\a x2,
-    \a y2).
+    \a y2). All parameters must be finite.
 
     \sa getCoords(), setRect()
 */
@@ -1882,6 +1882,7 @@ QRectF QRectF::normalized() const noexcept
 
     Returns a new rectangle with \a dx1, \a dy1, \a dx2 and \a dy2
     added respectively to the existing coordinates of this rectangle.
+    All parameters must be finite.
 
     \sa adjust()
 */
@@ -1889,7 +1890,7 @@ QRectF QRectF::normalized() const noexcept
 /*! \fn void QRectF::adjust(qreal dx1, qreal dy1, qreal dx2, qreal dy2)
 
     Adds \a dx1, \a dy1, \a dx2 and \a dy2 respectively to the
-    existing coordinates of the rectangle.
+    existing coordinates of the rectangle. All parameters must be finite.
 
     \sa adjusted(), setRect()
 */
@@ -1920,7 +1921,7 @@ QRectF QRectF::normalized() const noexcept
 /*!
     \fn void QRectF::setWidth(qreal width)
 
-    Sets the width of the rectangle to the given \a width. The right
+    Sets the width of the rectangle to the given finite \a width. The right
     edge is changed, but not the left one.
 
     \sa width(), setSize()
@@ -1930,7 +1931,7 @@ QRectF QRectF::normalized() const noexcept
 /*!
     \fn void QRectF::setHeight(qreal height)
 
-    Sets the height of the rectangle to the given \a height. The bottom
+    Sets the height of the rectangle to the given finite \a height. The bottom
     edge is changed, but not the top one.
 
     \sa height(), setSize()
@@ -1940,7 +1941,7 @@ QRectF QRectF::normalized() const noexcept
 /*!
     \fn void QRectF::setSize(const QSizeF &size)
 
-    Sets the size of the rectangle to the given \a size. The top-left
+    Sets the size of the rectangle to the given finite \a size. The top-left
     corner is not moved.
 
     \sa size(), setWidth(), setHeight()
diff --git a/src/corelib/tools/qrect.h b/src/corelib/tools/qrect.h
index da80106e3e6..9e64f4d6e81 100644
--- a/src/corelib/tools/qrect.h
+++ b/src/corelib/tools/qrect.h
@@ -769,7 +769,9 @@ constexpr inline void QRectF::moveTo(const QPointF &p) noexcept
 }
 
 constexpr inline QRectF QRectF::translated(qreal dx, qreal dy) const noexcept
-{ return QRectF(xp + dx, yp + dy, w, h); }
+{
+    return QRectF(xp + dx, yp + dy, w, h);
+}
 
 constexpr inline QRectF QRectF::translated(const QPointF &p) const noexcept
 { return QRectF(xp + p.x(), yp + p.y(), w, h); }
@@ -810,10 +812,17 @@ constexpr inline void QRectF::setCoords(qreal xp1, qreal yp1, qreal xp2, qreal y
 }
 
 constexpr inline void QRectF::adjust(qreal xp1, qreal yp1, qreal xp2, qreal yp2) noexcept
-{ xp += xp1; yp += yp1; w += xp2 - xp1; h += yp2 - yp1; }
+{
+    xp += xp1;
+    yp += yp1;
+    w += xp2 - xp1;
+    h += yp2 - yp1;
+}
 
 constexpr inline QRectF QRectF::adjusted(qreal xp1, qreal yp1, qreal xp2, qreal yp2) const noexcept
-{ return QRectF(xp + xp1, yp + yp1, w + xp2 - xp1, h + yp2 - yp1); }
+{
+    return QRectF(xp + xp1, yp + yp1, w + xp2 - xp1, h + yp2 - yp1);
+}
 
 constexpr inline void QRectF::setWidth(qreal aw) noexcept
 { this->w = aw; }
diff --git a/src/corelib/tools/qsize.cpp b/src/corelib/tools/qsize.cpp
index 788356002c9..2779948aaec 100644
--- a/src/corelib/tools/qsize.cpp
+++ b/src/corelib/tools/qsize.cpp
@@ -526,7 +526,7 @@ QDebug operator<<(QDebug dbg, const QSize &s)
 /*!
     \fn QSizeF::QSizeF(qreal width, qreal height)
 
-    Constructs a size with the given \a width and \a height.
+    Constructs a size with the given finite \a width and \a height.
 */
 
 /*!
@@ -550,7 +550,7 @@ QDebug operator<<(QDebug dbg, const QSize &s)
 /*!
     \fn bool QSizeF::isValid() const
 
-    Returns \c true if both the width and height is equal to or greater
+    Returns \c true if both the width and height are equal to or greater
     than 0; otherwise returns \c false.
 
     \sa isNull(), isEmpty()
@@ -575,7 +575,7 @@ QDebug operator<<(QDebug dbg, const QSize &s)
 /*!
     \fn void QSizeF::setWidth(qreal width)
 
-    Sets the width to the given \a width.
+    Sets the width to the given finite \a width.
 
     \sa width(), rwidth(), setHeight()
 */
@@ -583,7 +583,7 @@ QDebug operator<<(QDebug dbg, const QSize &s)
 /*!
     \fn void QSizeF::setHeight(qreal height)
 
-    Sets the height to the given \a height.
+    Sets the height to the given finite \a height.
 
     \sa height(), rheight(), setWidth()
 */
@@ -734,7 +734,7 @@ QSizeF QSizeF::scaled(const QSizeF &s, Qt::AspectRatioMode mode) const noexcept
     \fn QSizeF &QSizeF::operator*=(qreal factor)
     \overload
 
-    Multiplies both the width and height by the given \a factor and
+    Multiplies both the width and height by the given finite \a factor and
     returns a reference to the size.
 
     \sa scale()
@@ -780,7 +780,7 @@ QSizeF QSizeF::scaled(const QSizeF &s, Qt::AspectRatioMode mode) const noexcept
 
     \overload
 
-    Multiplies the given \a size by the given \a factor and returns
+    Multiplies the given \a size by the given finite \a factor and returns
     the result.
 
     \sa QSizeF::scale()
@@ -791,7 +791,7 @@ QSizeF QSizeF::scaled(const QSizeF &s, Qt::AspectRatioMode mode) const noexcept
 
     \overload
 
-    Multiplies the given \a size by the given \a factor and returns
+    Multiplies the given \a size by the given finite \a factor and returns
     the result.
 */
 
@@ -800,8 +800,8 @@ QSizeF QSizeF::scaled(const QSizeF &s, Qt::AspectRatioMode mode) const noexcept
 
     \overload
 
-    Divides both the width and height by the given \a divisor and
-    returns a reference to the size.
+    Divides both the width and height by the given \a divisor and returns a
+    reference to the size. The \a divisor must not be either zero or NaN.
 
     \sa scale()
 */
@@ -812,7 +812,7 @@ QSizeF QSizeF::scaled(const QSizeF &s, Qt::AspectRatioMode mode) const noexcept
     \overload
 
     Divides the given \a size by the given \a divisor and returns the
-    result.
+    result. The \a divisor must not be either zero or NaN.
 
     \sa QSizeF::scale()
 */
diff --git a/src/corelib/tools/qsize.h b/src/corelib/tools/qsize.h
index a11169c53c9..23b4396d797 100644
--- a/src/corelib/tools/qsize.h
+++ b/src/corelib/tools/qsize.h
@@ -375,7 +375,7 @@ constexpr inline QSizeF &QSizeF::operator*=(qreal c) noexcept
 
 inline QSizeF &QSizeF::operator/=(qreal c)
 {
-    Q_ASSERT(!qFuzzyIsNull(c));
+    Q_ASSERT(!qFuzzyIsNull(c) && qIsFinite(c));
     wd = wd / c;
     ht = ht / c;
     return *this;
diff --git a/src/gui/math3d/qvectornd.cpp b/src/gui/math3d/qvectornd.cpp
index 1c456a9d6d3..28e8f9ff675 100644
--- a/src/gui/math3d/qvectornd.cpp
+++ b/src/gui/math3d/qvectornd.cpp
@@ -56,6 +56,10 @@ QT_BEGIN_NAMESPACE
     \ingroup painting-3D
     \inmodule QtGui
 
+    Vectors are one of the main building blocks of 2D representation and
+    drawing. They consist of two finite floating-point coordinates,
+    traditionally called x and y.
+
     The QVector2D class can also be used to represent vertices in 2D space.
     We therefore do not need to provide a separate vertex class.
 
@@ -80,6 +84,7 @@ QT_BEGIN_NAMESPACE
     \fn QVector2D::QVector2D(float xpos, float ypos)
 
     Constructs a vector with coordinates (\a xpos, \a ypos).
+    Both coordinates must be finite.
 */
 
 /*!
@@ -146,7 +151,7 @@ QT_BEGIN_NAMESPACE
 /*!
     \fn void QVector2D::setX(float x)
 
-    Sets the x coordinate of this point to the given \a x coordinate.
+    Sets the x coordinate of this point to the given finite \a x coordinate.
 
     \sa x(), setY()
 */
@@ -154,7 +159,7 @@ QT_BEGIN_NAMESPACE
 /*!
     \fn void QVector2D::setY(float y)
 
-    Sets the y coordinate of this point to the given \a y coordinate.
+    Sets the y coordinate of this point to the given finite \a y coordinate.
 
     \sa y(), setX()
 */
@@ -260,7 +265,7 @@ QT_BEGIN_NAMESPACE
 /*!
     \fn QVector2D &QVector2D::operator*=(float factor)
 
-    Multiplies this vector's coordinates by the given \a factor, and
+    Multiplies this vector's coordinates by the given finite \a factor and
     returns a reference to this vector.
 
     \sa operator/=()
@@ -276,8 +281,8 @@ QT_BEGIN_NAMESPACE
 /*!
     \fn QVector2D &QVector2D::operator/=(float divisor)
 
-    Divides this vector's coordinates by the given \a divisor, and
-    returns a reference to this vector.
+    Divides this vector's coordinates by the given \a divisor and returns a
+    reference to this vector. The \a divisor must not be either zero or NaN.
 
     \sa operator*=()
 */
@@ -286,10 +291,12 @@ QT_BEGIN_NAMESPACE
     \fn QVector2D &QVector2D::operator/=(QVector2D vector)
     \since 5.5
 
-    Divides the components of this vector by the corresponding
-    components in \a vector.
+    Divides each component of this vector by the corresponding component of \a
+    vector and returns a reference to this vector.
 
-    \sa operator*=()
+    The \a vector must have no component that is either zero or NaN.
+
+    \sa operator*=(), operator/()
 */
 
 /*!
@@ -333,7 +340,7 @@ QT_BEGIN_NAMESPACE
 /*! //! friend
     \fn const QVector2D QVector2D::operator*(float factor, QVector2D vector)
 
-    Returns a copy of the given \a vector,  multiplied by the given \a factor.
+    Returns a copy of the given \a vector, multiplied by the given finite \a factor.
 
     \sa QVector2D::operator*=()
 */
@@ -341,7 +348,7 @@ QT_BEGIN_NAMESPACE
 /*! //! friend
     \fn const QVector2D QVector2D::operator*(QVector2D vector, float factor)
 
-    Returns a copy of the given \a vector,  multiplied by the given \a factor.
+    Returns a copy of the given \a vector, multiplied by the given finite \a factor.
 
     \sa QVector2D::operator*=()
 */
@@ -366,8 +373,10 @@ QT_BEGIN_NAMESPACE
 /*! //! friend
     \fn const QVector2D QVector2D::operator/(QVector2D vector, float divisor)
 
-    Returns the QVector2D object formed by dividing all three components of
-    the given \a vector by the given \a divisor.
+    Returns the QVector2D object formed by dividing each component of the given
+    \a vector by the given \a divisor.
+
+    The \a divisor must not be either zero or NaN.
 
     \sa QVector2D::operator/=()
 */
@@ -376,8 +385,10 @@ QT_BEGIN_NAMESPACE
     \fn const QVector2D QVector2D::operator/(QVector2D vector, QVector2D divisor)
     \since 5.5
 
-    Returns the QVector2D object formed by dividing components of the given
-    \a vector by a respective components of the given \a divisor.
+    Returns the QVector2D object formed by dividing each component of the given
+    \a vector by the corresponding component of the given \a divisor.
+
+    The \a divisor must have no component that is either zero or NaN.
 
     \sa QVector2D::operator/=()
 */
@@ -481,6 +492,7 @@ QDataStream &operator>>(QDataStream &stream, QVector2D &vector)
     float x, y;
     stream >> x;
     stream >> y;
+    Q_ASSERT(qIsFinite(x) && qIsFinite(y));
     vector.setX(x);
     vector.setY(y);
     return stream;
@@ -502,8 +514,8 @@ QDataStream &operator>>(QDataStream &stream, QVector2D &vector)
     \inmodule QtGui
 
     Vectors are one of the main building blocks of 3D representation and
-    drawing. They consist of three coordinates, traditionally called
-    x, y, and z.
+    drawing. They consist of three finite floating-point coordinates,
+    traditionally called x, y, and z.
 
     The QVector3D class can also be used to represent vertices in 3D space.
     We therefore do not need to provide a separate vertex class.
@@ -529,6 +541,7 @@ QDataStream &operator>>(QDataStream &stream, QVector2D &vector)
     \fn QVector3D::QVector3D(float xpos, float ypos, float zpos)
 
     Constructs a vector with coordinates (\a xpos, \a ypos, \a zpos).
+    All parameters must be finite.
 */
 
 /*!
@@ -560,7 +573,7 @@ QDataStream &operator>>(QDataStream &stream, QVector2D &vector)
     \fn QVector3D::QVector3D(QVector2D vector, float zpos)
 
     Constructs a 3D vector from the specified 2D \a vector. The z
-    coordinate is set to \a zpos.
+    coordinate is set to \a zpos, which must be finite.
 
     \sa toVector2D()
 */
@@ -613,7 +626,7 @@ QDataStream &operator>>(QDataStream &stream, QVector2D &vector)
 /*!
     \fn void QVector3D::setX(float x)
 
-    Sets the x coordinate of this point to the given \a x coordinate.
+    Sets the x coordinate of this point to the given finite \a x coordinate.
 
     \sa x(), setY(), setZ()
 */
@@ -621,7 +634,7 @@ QDataStream &operator>>(QDataStream &stream, QVector2D &vector)
 /*!
     \fn void QVector3D::setY(float y)
 
-    Sets the y coordinate of this point to the given \a y coordinate.
+    Sets the y coordinate of this point to the given finite \a y coordinate.
 
     \sa y(), setX(), setZ()
 */
@@ -629,7 +642,7 @@ QDataStream &operator>>(QDataStream &stream, QVector2D &vector)
 /*!
     \fn void QVector3D::setZ(float z)
 
-    Sets the z coordinate of this point to the given \a z coordinate.
+    Sets the z coordinate of this point to the given finite \a z coordinate.
 
     \sa z(), setX(), setY()
 */
@@ -695,7 +708,7 @@ QDataStream &operator>>(QDataStream &stream, QVector2D &vector)
 /*!
     \fn QVector3D &QVector3D::operator*=(float factor)
 
-    Multiplies this vector's coordinates by the given \a factor, and
+    Multiplies this vector's coordinates by the given finite \a factor and
     returns a reference to this vector.
 
     \sa operator/=()
@@ -717,8 +730,8 @@ QDataStream &operator>>(QDataStream &stream, QVector2D &vector)
 /*!
     \fn QVector3D &QVector3D::operator/=(float divisor)
 
-    Divides this vector's coordinates by the given \a divisor, and
-    returns a reference to this vector.
+    Divides this vector's coordinates by the given \a divisor, and returns a
+    reference to this vector. The \a divisor must not be either zero or NaN.
 
     \sa operator*=()
 */
@@ -727,8 +740,10 @@ QDataStream &operator>>(QDataStream &stream, QVector2D &vector)
     \fn QVector3D &QVector3D::operator/=(QVector3D vector)
     \since 5.5
 
-    Divides the components of this vector by the corresponding
-    components in \a vector.
+    Divides each component of this vector by the corresponding component in \a
+    vector and returns a reference to this vector.
+
+    The \a vector must have no component that is either zero or NaN.
 
     \sa operator*=()
 */
@@ -751,8 +766,8 @@ QDataStream &operator>>(QDataStream &stream, QVector2D &vector)
 /*!
     \fn QVector3D QVector3D::normal(QVector3D v1, QVector3D v2)
 
-    Returns the normal vector of a plane defined by vectors \a v1 and \a v2,
-    normalized to be a unit vector.
+    Returns the unit normal vector of a plane spanned by vectors \a v1 and \a
+    v2, which must not be parallel to one another.
 
     Use crossProduct() to compute the cross-product of \a v1 and \a v2 if you
     do not need the result to be normalized to a unit vector.
@@ -763,8 +778,8 @@ QDataStream &operator>>(QDataStream &stream, QVector2D &vector)
 /*!
     \fn QVector3D QVector3D::normal(QVector3D v1, QVector3D v2, QVector3D v3)
 
-    Returns the normal vector of a plane defined by vectors
-    \a v2 - \a v1 and \a v3 - \a v1, normalized to be a unit vector.
+    Returns the unit normal vector of a plane spanned by vectors \a v2 - \a v1
+    and \a v3 - \a v1, which must not be parallel to one another.
 
     Use crossProduct() to compute the cross-product of \a v2 - \a v1 and
     \a v3 - \a v1 if you do not need the result to be normalized to a
@@ -922,7 +937,7 @@ QVector3D QVector3D::unproject(const QMatrix4x4 &modelView, const QMatrix4x4 &pr
 /*! //! friend
     \fn const QVector3D QVector3D::operator*(float factor, QVector3D vector)
 
-    Returns a copy of the given \a vector,  multiplied by the given \a factor.
+    Returns a copy of the given \a vector, multiplied by the given finite \a factor.
 
     \sa QVector3D::operator*=()
 */
@@ -930,7 +945,7 @@ QVector3D QVector3D::unproject(const QMatrix4x4 &modelView, const QMatrix4x4 &pr
 /*! //! friend
     \fn const QVector3D QVector3D::operator*(QVector3D vector, float factor)
 
-    Returns a copy of the given \a vector,  multiplied by the given \a factor.
+    Returns a copy of the given \a vector, multiplied by the given finite \a factor.
 
     \sa QVector3D::operator*=()
 */
@@ -958,8 +973,10 @@ QVector3D QVector3D::unproject(const QMatrix4x4 &modelView, const QMatrix4x4 &pr
 /*! //! friend
     \fn const QVector3D QVector3D::operator/(QVector3D vector, float divisor)
 
-    Returns the QVector3D object formed by dividing all three components of
-    the given \a vector by the given \a divisor.
+    Returns the QVector3D object formed by dividing each component of the given
+    \a vector by the given \a divisor.
+
+    The \a divisor must not be either zero or NaN.
 
     \sa QVector3D::operator/=()
 */
@@ -968,8 +985,10 @@ QVector3D QVector3D::unproject(const QMatrix4x4 &modelView, const QMatrix4x4 &pr
     \fn const QVector3D QVector3D::operator/(QVector3D vector, QVector3D divisor)
     \since 5.5
 
-    Returns the QVector3D object formed by dividing components of the given
-    \a vector by a respective components of the given \a divisor.
+    Returns the QVector3D object formed by dividing each component of the given
+    \a vector by the corresponding component of the given \a divisor.
+
+    The \a divisor must have no component that is either zero or NaN.
 
     \sa QVector3D::operator/=()
 */
@@ -1100,6 +1119,7 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
     stream >> x;
     stream >> y;
     stream >> z;
+    Q_ASSERT(qIsFinite(x) && qIsFinite(y) && qIsFinite(z));
     vector.setX(x);
     vector.setY(y);
     vector.setZ(z);
@@ -1121,6 +1141,10 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
     \ingroup painting-3D
     \inmodule QtGui
 
+    Vectors are one of the main building blocks of 4D affine representations of
+    3D space. They consist of four finite floating-point coordinates,
+    traditionally called x, y, z and w.
+
     The QVector4D class can also be used to represent vertices in 4D space.
     We therefore do not need to provide a separate vertex class.
 
@@ -1145,6 +1169,7 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
     \fn QVector4D::QVector4D(float xpos, float ypos, float zpos, float wpos)
 
     Constructs a vector with coordinates (\a xpos, \a ypos, \a zpos, \a wpos).
+    All parameters must be finite.
 */
 
 /*!
@@ -1176,7 +1201,8 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
     \fn QVector4D::QVector4D(QVector2D vector, float zpos, float wpos)
 
     Constructs a 4D vector from the specified 2D \a vector. The z
-    and w coordinates are set to \a zpos and \a wpos respectively.
+    and w coordinates are set to \a zpos and \a wpos respectively,
+    each of which must be finite.
 
     \sa toVector2D()
 */
@@ -1198,7 +1224,7 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
     \fn QVector4D::QVector4D(QVector3D vector, float wpos)
 
     Constructs a 4D vector from the specified 3D \a vector. The w
-    coordinate is set to \a wpos.
+    coordinate is set to \a wpos, which must be finite.
 
     \sa toVector3D()
 */
@@ -1247,7 +1273,7 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
 /*!
     \fn void QVector4D::setX(float x)
 
-    Sets the x coordinate of this point to the given \a x coordinate.
+    Sets the x coordinate of this point to the given finite \a x coordinate.
 
     \sa x(), setY(), setZ(), setW()
 */
@@ -1255,7 +1281,7 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
 /*!
     \fn void QVector4D::setY(float y)
 
-    Sets the y coordinate of this point to the given \a y coordinate.
+    Sets the y coordinate of this point to the given finite \a y coordinate.
 
     \sa y(), setX(), setZ(), setW()
 */
@@ -1263,7 +1289,7 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
 /*!
     \fn void QVector4D::setZ(float z)
 
-    Sets the z coordinate of this point to the given \a z coordinate.
+    Sets the z coordinate of this point to the given finite \a z coordinate.
 
     \sa z(), setX(), setY(), setW()
 */
@@ -1271,7 +1297,7 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
 /*!
     \fn void QVector4D::setW(float w)
 
-    Sets the w coordinate of this point to the given \a w coordinate.
+    Sets the w coordinate of this point to the given finite \a w coordinate.
 
     \sa w(), setX(), setY(), setZ()
 */
@@ -1355,7 +1381,7 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
 /*!
     \fn QVector4D &QVector4D::operator*=(float factor)
 
-    Multiplies this vector's coordinates by the given \a factor, and
+    Multiplies this vector's coordinates by the given finite \a factor, and
     returns a reference to this vector.
 
     \sa operator/=()
@@ -1371,8 +1397,8 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
 /*!
     \fn QVector4D &QVector4D::operator/=(float divisor)
 
-    Divides this vector's coordinates by the given \a divisor, and
-    returns a reference to this vector.
+    Divides this vector's coordinates by the given \a divisor, and returns a
+    reference to this vector. The \a divisor must not be either zero or NaN.
 
     \sa operator*=()
 */
@@ -1381,8 +1407,10 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
     \fn QVector4D &QVector4D::operator/=(QVector4D vector)
     \since 5.5
 
-    Divides the components of this vector by the corresponding
-    components in \a vector.
+    Divides each component of this vector by the corresponding component of \a
+    vector and returns a reference to this vector.
+
+    The \a vector must have no component that is either zero or NaN.
 
     \sa operator*=()
 */
@@ -1463,8 +1491,10 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
 /*! //! friend
     \fn const QVector4D QVector4D::operator/(QVector4D vector, float divisor)
 
-    Returns the QVector4D object formed by dividing all four components of
-    the given \a vector by the given \a divisor.
+    Returns the QVector4D object formed by dividing each component of the given
+    \a vector by the given \a divisor.
+
+    The \a divisor must not be either zero or NaN.
 
     \sa QVector4D::operator/=()
 */
@@ -1473,8 +1503,10 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
     \fn const QVector4D QVector4D::operator/(QVector4D vector, QVector4D divisor)
     \since 5.5
 
-    Returns the QVector4D object formed by dividing components of the given
-    \a vector by a respective components of the given \a divisor.
+    Returns the QVector4D object formed by dividing each component of the given
+    \a vector by the corresponding component of the given \a divisor.
+
+    The \a divisor must have no component that is either zero or NaN.
 
     \sa QVector4D::operator/=()
 */
@@ -1611,6 +1643,7 @@ QDataStream &operator>>(QDataStream &stream, QVector4D &vector)
     stream >> y;
     stream >> z;
     stream >> w;
+    Q_ASSERT(qIsFinite(x) && qIsFinite(y) && qIsFinite(z) && qIsFinite(w));
     vector.setX(x);
     vector.setY(y);
     vector.setZ(z);
diff --git a/src/gui/math3d/qvectornd.h b/src/gui/math3d/qvectornd.h
index 8d2789338cb..153f3743d8f 100644
--- a/src/gui/math3d/qvectornd.h
+++ b/src/gui/math3d/qvectornd.h
@@ -147,11 +147,14 @@ QT_WARNING_POP
 
     constexpr friend inline QVector2D operator/(QVector2D vector, float divisor)
     {
+        Q_ASSERT(divisor < 0 || divisor > 0);
         return QVector2D(vector.v[0] / divisor, vector.v[1] / divisor);
     }
 
     constexpr friend inline QVector2D operator/(QVector2D vector, QVector2D divisor)
     {
+        Q_ASSERT(divisor.v[0] < 0 || divisor.v[0] > 0);
+        Q_ASSERT(divisor.v[1] < 0 || divisor.v[1] > 0);
         return QVector2D(vector.v[0] / divisor.v[0], vector.v[1] / divisor.v[1]);
     }
 
@@ -288,12 +291,17 @@ QT_WARNING_POP
 
     constexpr friend inline QVector3D operator/(QVector3D vector, float divisor)
     {
+        Q_ASSERT(divisor < 0 || divisor > 0);
         return QVector3D(vector.v[0] / divisor, vector.v[1] / divisor, vector.v[2] / divisor);
     }
 
     constexpr friend inline QVector3D operator/(QVector3D vector, QVector3D divisor)
     {
-        return QVector3D(vector.v[0] / divisor.v[0], vector.v[1] / divisor.v[1], vector.v[2] / divisor.v[2]);
+        Q_ASSERT(divisor.v[0] > 0 || divisor.v[0] < 0);
+        Q_ASSERT(divisor.v[1] > 0 || divisor.v[1] < 0);
+        Q_ASSERT(divisor.v[2] > 0 || divisor.v[2] < 0);
+        return QVector3D(vector.v[0] / divisor.v[0], vector.v[1] / divisor.v[1],
+                         vector.v[2] / divisor.v[2]);
     }
 
     friend Q_GUI_EXPORT bool qFuzzyCompare(QVector3D v1, QVector3D v2) noexcept;
@@ -422,12 +430,18 @@ QT_WARNING_POP
 
     constexpr friend inline QVector4D operator/(QVector4D vector, float divisor)
     {
+        Q_ASSERT(divisor < 0 || divisor > 0);
         return QVector4D(vector.v[0] / divisor, vector.v[1] / divisor, vector.v[2] / divisor, vector.v[3] / divisor);
     }
 
     constexpr friend inline QVector4D operator/(QVector4D vector, QVector4D divisor)
     {
-        return QVector4D(vector.v[0] / divisor.v[0], vector.v[1] / divisor.v[1], vector.v[2] / divisor.v[2], vector.v[3] / divisor.v[3]);
+        Q_ASSERT(divisor.v[0] > 0 || divisor.v[0] < 0);
+        Q_ASSERT(divisor.v[1] > 0 || divisor.v[1] < 0);
+        Q_ASSERT(divisor.v[2] > 0 || divisor.v[2] < 0);
+        Q_ASSERT(divisor.v[3] > 0 || divisor.v[3] < 0);
+        return QVector4D(vector.v[0] / divisor.v[0], vector.v[1] / divisor.v[1],
+                         vector.v[2] / divisor.v[2], vector.v[3] / divisor.v[3]);
     }
 
     friend Q_GUI_EXPORT bool qFuzzyCompare(QVector4D v1, QVector4D v2) noexcept;
@@ -576,6 +590,7 @@ constexpr inline QVector2D &QVector2D::operator*=(QVector2D vector) noexcept
 
 constexpr inline QVector2D &QVector2D::operator/=(float divisor)
 {
+    Q_ASSERT(divisor < 0 || divisor > 0);
     v[0] /= divisor;
     v[1] /= divisor;
     return *this;
@@ -583,6 +598,8 @@ constexpr inline QVector2D &QVector2D::operator/=(float divisor)
 
 constexpr inline QVector2D &QVector2D::operator/=(QVector2D vector)
 {
+    Q_ASSERT(vector.v[0] > 0 || vector.v[0] < 0);
+    Q_ASSERT(vector.v[1] > 0 || vector.v[1] < 0);
     v[0] /= vector.v[0];
     v[1] /= vector.v[1];
     return *this;
@@ -736,6 +753,7 @@ constexpr inline QVector3D &QVector3D::operator*=(QVector3D vector) noexcept
 
 constexpr inline QVector3D &QVector3D::operator/=(float divisor)
 {
+    Q_ASSERT(divisor < 0 || divisor > 0);
     v[0] /= divisor;
     v[1] /= divisor;
     v[2] /= divisor;
@@ -744,6 +762,9 @@ constexpr inline QVector3D &QVector3D::operator/=(float divisor)
 
 constexpr inline QVector3D &QVector3D::operator/=(QVector3D vector)
 {
+    Q_ASSERT(vector.v[0] > 0 || vector.v[0] < 0);
+    Q_ASSERT(vector.v[1] > 0 || vector.v[1] < 0);
+    Q_ASSERT(vector.v[2] > 0 || vector.v[2] < 0);
     v[0] /= vector.v[0];
     v[1] /= vector.v[1];
     v[2] /= vector.v[2];
@@ -947,6 +968,7 @@ constexpr inline QVector4D &QVector4D::operator*=(QVector4D vector) noexcept
 
 constexpr inline QVector4D &QVector4D::operator/=(float divisor)
 {
+    Q_ASSERT(divisor < 0 || divisor > 0);
     v[0] /= divisor;
     v[1] /= divisor;
     v[2] /= divisor;
@@ -956,6 +978,10 @@ constexpr inline QVector4D &QVector4D::operator/=(float divisor)
 
 constexpr inline QVector4D &QVector4D::operator/=(QVector4D vector)
 {
+    Q_ASSERT(vector.v[0] > 0 || vector.v[0] < 0);
+    Q_ASSERT(vector.v[1] > 0 || vector.v[1] < 0);
+    Q_ASSERT(vector.v[2] > 0 || vector.v[2] < 0);
+    Q_ASSERT(vector.v[3] > 0 || vector.v[3] < 0);
     v[0] /= vector.v[0];
     v[1] /= vector.v[1];
     v[2] /= vector.v[2];