diff --git a/CMakeLists.txt b/CMakeLists.txt
index c1b77656f672b56bb72870b52dcd0e01c7c365f7..1d0585943576ea5dd6234323b933f35b37da4602 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -845,6 +845,7 @@ option (WALBERLA_ENABLE_GUI "This flag builds the graphical user interface, depe
 
 if ( WALBERLA_ENABLE_GUI )
 
+    message( WARNING "The GUI is deprecated and will probably not work correctly." )
     find_package( Qt4 COMPONENTS QtCore QtGui QtOpenGL QtXml REQUIRED )
     set( OpenGL_GL_PREFERENCE LEGACY )
     find_package( OpenGL REQUIRED )