diff --git a/src/Mod/Mesh/Gui/SoFCIndexedFaceSet.cpp b/src/Mod/Mesh/Gui/SoFCIndexedFaceSet.cpp
index 7f401e15ba..b3174a0b2c 100644
--- a/src/Mod/Mesh/Gui/SoFCIndexedFaceSet.cpp
+++ b/src/Mod/Mesh/Gui/SoFCIndexedFaceSet.cpp
@@ -23,6 +23,10 @@
 
 #include "PreCompiled.h"
 
+#ifndef FC_OS_WIN32
+#define GL_GLEXT_PROTOTYPES
+#endif
+
 #ifndef _PreComp_
 # include <algorithm>
 # ifdef FC_OS_MACOSX