--- a/UserInterface/MainComponents/UserInterfaceBase.h
+++ b/UserInterface/MainComponents/UserInterfaceBase.h
@@ -38,7 +38,7 @@
 // This should all be gone
 #include "SNAPCommonUI.h"
 #include "GlobalState.h" 
-#include "FL/Fl_Double_Window.h"
+#include "FL/Fl_Double_Window.H"
 
 // Borland compiler stuff. Note to whoever went through the code and added all 
 // these borland things: you just can't add ITK headers to headers like this one
