diff --git a/src/plugins/qmldesigner/components/curveeditor/curveeditormodel.h b/src/plugins/qmldesigner/components/curveeditor/curveeditormodel.h
index 840107ced5d..6e212d4c6af 100644
--- a/src/plugins/qmldesigner/components/curveeditor/curveeditormodel.h
+++ b/src/plugins/qmldesigner/components/curveeditor/curveeditormodel.h
@@ -29,7 +29,9 @@
 
 #include <vector>
 
+QT_BEGIN_NAMESPACE
 class QPointF;
+QT_END_NAMESPACE
 
 namespace DesignTools {
 
diff --git a/src/plugins/qmldesigner/components/curveeditor/detail/curveeditorstyledialog.h b/src/plugins/qmldesigner/components/curveeditor/detail/curveeditorstyledialog.h
index ad5a28e2e13..f1dc3bc3728 100644
--- a/src/plugins/qmldesigner/components/curveeditor/detail/curveeditorstyledialog.h
+++ b/src/plugins/qmldesigner/components/curveeditor/detail/curveeditorstyledialog.h
@@ -28,9 +28,11 @@
 
 #include <QDialog>
 
+QT_BEGIN_NAMESPACE
 class QPushButton;
 class QSpinBox;
 class QDoubleSpinBox;
+QT_END_NAMESPACE
 
 namespace DesignTools {
 
diff --git a/src/plugins/qmldesigner/components/curveeditor/detail/curvesegment.h b/src/plugins/qmldesigner/components/curveeditor/detail/curvesegment.h
index ce2d700f891..5dbce58bccd 100644
--- a/src/plugins/qmldesigner/components/curveeditor/detail/curvesegment.h
+++ b/src/plugins/qmldesigner/components/curveeditor/detail/curvesegment.h
@@ -29,7 +29,9 @@
 
 #include <vector>
 
+QT_BEGIN_NAMESPACE
 class QPointF;
+QT_END_NAMESPACE
 
 namespace DesignTools {
 
diff --git a/src/plugins/qmldesigner/components/curveeditor/detail/playhead.h b/src/plugins/qmldesigner/components/curveeditor/detail/playhead.h
index ffb4da4cfdc..28d2a21a5c3 100644
--- a/src/plugins/qmldesigner/components/curveeditor/detail/playhead.h
+++ b/src/plugins/qmldesigner/components/curveeditor/detail/playhead.h
@@ -28,7 +28,9 @@
 #include <QRectF>
 #include <QTimer>
 
+QT_BEGIN_NAMESPACE
 class QPainter;
+QT_END_NAMESPACE
 
 namespace DesignTools {
 
diff --git a/src/plugins/qmldesigner/components/curveeditor/detail/utils.h b/src/plugins/qmldesigner/components/curveeditor/detail/utils.h
index 812c5d083ac..77cbd2c7bf2 100644
--- a/src/plugins/qmldesigner/components/curveeditor/detail/utils.h
+++ b/src/plugins/qmldesigner/components/curveeditor/detail/utils.h
@@ -25,11 +25,13 @@
 
 #pragma once
 
+QT_BEGIN_NAMESPACE
 class QColor;
 class QPalette;
 class QPointF;
 class QRectF;
 class QTransform;
+QT_END_NAMESPACE
 
 namespace DesignTools {
 
diff --git a/src/plugins/qmldesigner/components/curveeditor/treeitem.h b/src/plugins/qmldesigner/components/curveeditor/treeitem.h
index e5004834b8e..5b31dc2fc8c 100644
--- a/src/plugins/qmldesigner/components/curveeditor/treeitem.h
+++ b/src/plugins/qmldesigner/components/curveeditor/treeitem.h
@@ -33,8 +33,10 @@
 
 #include <vector>
 
+QT_BEGIN_NAMESPACE
 class QIcon;
 class QVariant;
+QT_END_NAMESPACE
 
 namespace DesignTools {