diff --git a/src/Mod/Part/Gui/DlgProjectionOnSurface.h b/src/Mod/Part/Gui/DlgProjectionOnSurface.h
index 51df4d79f5..d4d4fe9683 100644
--- a/src/Mod/Part/Gui/DlgProjectionOnSurface.h
+++ b/src/Mod/Part/Gui/DlgProjectionOnSurface.h
@@ -34,6 +34,7 @@
 #include "TopoDS_Edge.hxx"
 #include "TopoDS_Face.hxx"
 #include "TopoDS_Wire.hxx"
+#include "gp_Dir.hxx"
 
 namespace PartGui {