diff --git a/src/charts/glwidget_p.h b/src/charts/glwidget_p.h
index 156b86f..1beeb15 100644
--- a/src/charts/glwidget_p.h
+++ b/src/charts/glwidget_p.h
@@ -36,14 +36,13 @@
 #include <QtWidgets/QOpenGLWidget>
 #include <QtGui/QOpenGLFunctions>
 #include <QtGui/QOpenGLVertexArrayObject>
+#include <QtGui/QOpenGLBuffer>
 #include <QtCore/QHash>
 #include <QtCharts/QAbstractSeries>
 #include <QtCharts/QXYSeries>
 
 QT_FORWARD_DECLARE_CLASS(QOpenGLShaderProgram)
 
-class QOpenGLBuffer;
-
 QT_CHARTS_BEGIN_NAMESPACE
 
 class GLXYSeriesDataManager;
diff --git a/src/chartsqml2/declarativerendernode.h b/src/chartsqml2/declarativerendernode.h
index 4a443ac..47d4219 100644
--- a/src/chartsqml2/declarativerendernode.h
+++ b/src/chartsqml2/declarativerendernode.h
@@ -28,9 +28,8 @@
 #include <QtQuick/QQuickWindow>
 #include <QtGui/QOpenGLVertexArrayObject>
 #include <QtGui/QOpenGLFunctions>
-
-class QOpenGLFramebufferObject;
-class QOpenGLBuffer;
+#include <QtGui/QOpenGLFramebufferObject>
+#include <QtGui/QOpenGLBuffer>
 
 QT_CHARTS_BEGIN_NAMESPACE