diff --git a/libsrc/meshing/visual_interface.hpp b/libsrc/meshing/visual_interface.hpp
index e5da6521..5f856a24 100644
--- a/libsrc/meshing/visual_interface.hpp
+++ b/libsrc/meshing/visual_interface.hpp
@@ -21,16 +21,16 @@ typedef int (Tcl_CmdProc) (void * clientData, Tcl_Interp *interp,
 typedef void (Tcl_FreeProc) (char *blockPtr);
 
 namespace netgen {
-
   /*
-    inline constexpr int NG_TCL_VOLATILE = 1;
-    inline constexpr int NG_TCL_STATIC   = 0;
-    inline constexpr int NG_TCL_DYNAMIC  = 3;
+  inline constexpr int NG_TCL_VOLATILE = 1;
+  inline constexpr int NG_TCL_STATIC   = 0;
+  inline constexpr int NG_TCL_DYNAMIC  = 3;
   */
-#define TCL_VOLATILE		((Tcl_FreeProc *) 1)
-#define TCL_STATIC		((Tcl_FreeProc *) 0)
-#define TCL_DYNAMIC		((Tcl_FreeProc *) 3)
-  
+
+#define NG_TCL_VOLATILE		((Tcl_FreeProc *) 1)
+#define NG_TCL_STATIC		((Tcl_FreeProc *) 0)
+#define NG_TCL_DYNAMIC		((Tcl_FreeProc *) 3)
+
     inline constexpr int NG_TCL_OK       = 0;
     inline constexpr int NG_TCL_ERROR    = 1;
     inline constexpr int NG_TCL_RETURN   = 2;