diff --git a/src/testlib/qtestevent.h b/src/testlib/qtestevent.h
index faad914a474..50eff69edc0 100644
--- a/src/testlib/qtestevent.h
+++ b/src/testlib/qtestevent.h
@@ -58,6 +58,11 @@
 
 QT_BEGIN_NAMESPACE
 
+#ifdef QT_WIDGETS_LIB
+# define QT_ONLY_WIDGETLIB_USES
+#else
+# define QT_ONLY_WIDGETLIB_USES Q_DECL_UNUSED_MEMBER
+#endif
 
 class QTestEvent
 {
@@ -103,10 +108,7 @@ class QTestKeyClicksEvent: public QTestEvent
 {
 public:
     inline QTestKeyClicksEvent(const QString &keys, Qt::KeyboardModifiers modifiers, int delay)
-        : _keys(keys), _modifiers(modifiers), _delay(delay)
-        {
-            Q_UNUSED(_delay) // Silence -Werror,-Wunused-private-field
-        }
+        : _keys(keys), _modifiers(modifiers), _delay(delay) {}
     inline QTestEvent *clone() const override { return new QTestKeyClicksEvent(*this); }
 
 #ifdef QT_WIDGETS_LIB
@@ -117,9 +119,9 @@ public:
 #endif
 
 private:
-    QString _keys;
-    Qt::KeyboardModifiers _modifiers;
-    int _delay;
+    QT_ONLY_WIDGETLIB_USES QString _keys;
+    QT_ONLY_WIDGETLIB_USES Qt::KeyboardModifiers _modifiers;
+    QT_ONLY_WIDGETLIB_USES int _delay;
 };
 
 class QTestMouseEvent: public QTestEvent
@@ -127,12 +129,7 @@ class QTestMouseEvent: public QTestEvent
 public:
     inline QTestMouseEvent(QTest::MouseAction action, Qt::MouseButton button,
             Qt::KeyboardModifiers modifiers, QPoint position, int delay)
-        : _action(action), _button(button), _modifiers(modifiers), _pos(position), _delay(delay)
-        {
-            Q_UNUSED(_action)
-            Q_UNUSED(_button)
-            Q_UNUSED(_delay)
-        }
+        : _action(action), _button(button), _modifiers(modifiers), _pos(position), _delay(delay) {}
     inline QTestEvent *clone() const override { return new QTestMouseEvent(*this); }
 
 #ifdef QT_WIDGETS_LIB
@@ -143,11 +140,11 @@ public:
 #endif
 
 private:
-    QTest::MouseAction _action;
-    Qt::MouseButton _button;
-    Qt::KeyboardModifiers _modifiers;
-    QPoint _pos;
-    int _delay;
+    QT_ONLY_WIDGETLIB_USES QTest::MouseAction _action;
+    QT_ONLY_WIDGETLIB_USES Qt::MouseButton _button;
+    QT_ONLY_WIDGETLIB_USES Qt::KeyboardModifiers _modifiers;
+    QT_ONLY_WIDGETLIB_USES QPoint _pos;
+    QT_ONLY_WIDGETLIB_USES int _delay;
 };
 #endif //QT_GUI_LIB
 
@@ -155,10 +152,7 @@ private:
 class QTestDelayEvent: public QTestEvent
 {
 public:
-    inline QTestDelayEvent(int msecs): _delay(msecs)
-    {
-        Q_UNUSED(_delay)
-    }
+    inline QTestDelayEvent(int msecs): _delay(msecs) {}
     inline QTestEvent *clone() const override { return new QTestDelayEvent(*this); }
 
 #ifdef QT_WIDGETS_LIB
@@ -166,7 +160,7 @@ public:
 #endif
 
 private:
-    int _delay;
+    QT_ONLY_WIDGETLIB_USES int _delay;
 };
 
 class QTestEventList: public QList<QTestEvent *>
@@ -230,6 +224,8 @@ public:
 #endif
 };
 
+#undef QT_ONLY_WIDGETLIB_USES
+
 QT_END_NAMESPACE
 
 Q_DECLARE_METATYPE(QTestEventList)