diff --git a/src/corelib/kernel/qobject_p.h b/src/corelib/kernel/qobject_p.h
index 4b757b2bd93..66269b4c2ad 100644
--- a/src/corelib/kernel/qobject_p.h
+++ b/src/corelib/kernel/qobject_p.h
@@ -434,7 +434,9 @@ class QBoolBlocker
 {
     Q_DISABLE_COPY_MOVE(QBoolBlocker)
 public:
-    explicit inline QBoolBlocker(bool &b, bool value = true) : block(b), reset(b) { block = value; }
+    Q_NODISCARD_CTOR explicit QBoolBlocker(bool &b, bool value = true)
+        : block(b), reset(b)
+    { block = value; }
     inline ~QBoolBlocker() { block = reset; }
 
 private:
diff --git a/src/platformsupport/input/evdevkeyboard/qevdevkeyboardhandler_p.h b/src/platformsupport/input/evdevkeyboard/qevdevkeyboardhandler_p.h
index ed437c00600..1d991e2ba51 100644
--- a/src/platformsupport/input/evdevkeyboard/qevdevkeyboardhandler_p.h
+++ b/src/platformsupport/input/evdevkeyboard/qevdevkeyboardhandler_p.h
@@ -101,7 +101,7 @@ class QFdContainer
     int m_fd;
     Q_DISABLE_COPY_MOVE(QFdContainer);
 public:
-    explicit QFdContainer(int fd = -1) noexcept : m_fd(fd) {}
+    Q_NODISCARD_CTOR explicit QFdContainer(int fd = -1) noexcept : m_fd(fd) {}
     ~QFdContainer() { reset(); }
 
     int get() const noexcept { return m_fd; }
diff --git a/src/widgets/dialogs/qdialog_p.h b/src/widgets/dialogs/qdialog_p.h
index 878049557af..1d06c116fbb 100644
--- a/src/widgets/dialogs/qdialog_p.h
+++ b/src/widgets/dialogs/qdialog_p.h
@@ -103,7 +103,7 @@ template <typename T>
 class QAutoPointer {
     QPointer<T> o;
 public:
-    explicit QAutoPointer(T *t) noexcept : o(t) {}
+    Q_NODISCARD_CTOR explicit QAutoPointer(T *t) noexcept : o(t) {}
     ~QAutoPointer() { delete o; }
 
     T *operator->() const noexcept { return get(); }