diff --git a/FL/Fl_Device.H b/FL/Fl_Device.H
index 1fc5d0f56..fa924edef 100644
--- a/FL/Fl_Device.H
+++ b/FL/Fl_Device.H
@@ -32,7 +32,7 @@
 #include <FL/x.H>
 #include <FL/Fl_Plugin.H>
 #ifdef WIN32
-#include <Commdlg.h>
+#include <commdlg.h>
 #elif defined(__APPLE__)
 #else
 #include <stdio.h>