diff --git a/Source/NSFontManager.m b/Source/NSFontManager.m
index 8f9dc652d..55ac54211 100644
--- a/Source/NSFontManager.m
+++ b/Source/NSFontManager.m
@@ -29,6 +29,7 @@
 #include <gnustep/gui/config.h>
 #include <Foundation/NSArray.h>
 #include <Foundation/NSSet.h>
+#include <Foundation/NSDebug.h>
 #include <AppKit/NSFontManager.h>
 #include <AppKit/NSApplication.h>
 #include <AppKit/NSFont.h>