diff --git a/src/OpenMesh/Apps/QtViewer/MeshViewerWidgetT.hh b/src/OpenMesh/Apps/QtViewer/MeshViewerWidgetT.hh
index ead9a6e8..9fc7facd 100644
--- a/src/OpenMesh/Apps/QtViewer/MeshViewerWidgetT.hh
+++ b/src/OpenMesh/Apps/QtViewer/MeshViewerWidgetT.hh
@@ -57,6 +57,9 @@
 #include <OpenMesh/Tools/Utils/Timer.hh>
 #include <OpenMesh/Apps/QtViewer/QGLViewerWidget.hh>
 
+#ifndef __APPLE__
+  #include <GL/gl.h>
+#endif
 
 //== FORWARDS =================================================================
 
diff --git a/src/OpenMesh/Apps/QtViewer/QGLViewerWidget.hh b/src/OpenMesh/Apps/QtViewer/QGLViewerWidget.hh
index c0aa32b7..34d3a903 100644
--- a/src/OpenMesh/Apps/QtViewer/QGLViewerWidget.hh
+++ b/src/OpenMesh/Apps/QtViewer/QGLViewerWidget.hh
@@ -57,6 +57,10 @@
     #include <QtOpenGLWidgets/QOpenGLWidget>
 #endif
 
+#ifndef __APPLE__
+  #include <GL/gl.h>
+#endif
+
 //== FORWARD DECLARATIONS =====================================================
 
 class QMenu;