diff --git a/src/corelib/thread/qwaitcondition_p.h b/src/corelib/thread/qwaitcondition_p.h
index 0893e9dd351..cfb36ca30be 100644
--- a/src/corelib/thread/qwaitcondition_p.h
+++ b/src/corelib/thread/qwaitcondition_p.h
@@ -19,6 +19,11 @@
 #include <QtCore/QDeadlineTimer>
 #include <QtCore/private/qglobal_p.h>
 
+// This header always defines a class called "mutex" and one called
+// "condition_variable", so those mustn't be used to mark ELF symbol
+// visibility. Don't add more classes to this header!
+// ELFVERSION:stop
+
 #include <condition_variable>
 #include <mutex>
 
diff --git a/src/widgets/widgets/qmdisubwindow_p.h b/src/widgets/widgets/qmdisubwindow_p.h
index 60909eb3bcb..2a1f83269a5 100644
--- a/src/widgets/widgets/qmdisubwindow_p.h
+++ b/src/widgets/widgets/qmdisubwindow_p.h
@@ -39,7 +39,7 @@ class QMouseEvent;
 
 namespace QMdi {
 template<typename T>
-class ControlElement : public T
+class ControlElement : public T             // ELFVERSION:ignore
 {
 public:
     ControlElement(QMdiSubWindow *child) : T(child, nullptr)
@@ -58,7 +58,7 @@ public:
     QPointer<QMdiSubWindow> mdiChild;
 };
 
-class ControlContainer : public QObject
+class ControlContainer : public QObject     // ELFVERSION:ignore
 {
 public:
     ControlContainer(QMdiSubWindow *mdiChild);