diff --git a/src/Mod/Sandbox/Gui/CMakeLists.txt b/src/Mod/Sandbox/Gui/CMakeLists.txt
index 797b102004..f3cd24c276 100644
--- a/src/Mod/Sandbox/Gui/CMakeLists.txt
+++ b/src/Mod/Sandbox/Gui/CMakeLists.txt
@@ -10,7 +10,6 @@ if(BUILD_QT5)
         ${Qt5Core_INCLUDE_DIRS}
     )
 else()
-    SYSTEM
     include_directories(
         SYSTEM
         ${QT_INCLUDE_DIR}