diff --git a/examples/itemviews/spreadsheet/printview.h b/examples/itemviews/spreadsheet/printview.h
index 43a7bb39b7a..358aee008a2 100644
--- a/examples/itemviews/spreadsheet/printview.h
+++ b/examples/itemviews/spreadsheet/printview.h
@@ -43,7 +43,9 @@
 #define PRINTVIEW_H
 
 #include <QTableView>
+QT_BEGIN_NAMESPACE
 class QPrinter;
+QT_END_NAMESPACE
 
 class PrintView : public QTableView
 {
diff --git a/examples/opengl/hellowindow/hellowindow.h b/examples/opengl/hellowindow/hellowindow.h
index 371d60ac162..82d275aa684 100644
--- a/examples/opengl/hellowindow/hellowindow.h
+++ b/examples/opengl/hellowindow/hellowindow.h
@@ -46,7 +46,9 @@
 #include <QColor>
 #include <QTime>
 
+QT_BEGIN_NAMESPACE
 class QOpenGLContext;
+QT_END_NAMESPACE
 
 class Renderer : public QObject
 {
diff --git a/examples/opengl/paintedwindow/paintedwindow.h b/examples/opengl/paintedwindow/paintedwindow.h
index b5e9afbebb8..1792a0a7440 100644
--- a/examples/opengl/paintedwindow/paintedwindow.h
+++ b/examples/opengl/paintedwindow/paintedwindow.h
@@ -47,7 +47,9 @@
 #include <QColor>
 #include <QTime>
 
+QT_BEGIN_NAMESPACE
 class QOpenGLContext;
+QT_END_NAMESPACE
 
 class PaintedWindow : public QWindow
 {