diff --git a/src/servers/app/GlyphLayoutEngine.h b/src/servers/app/GlyphLayoutEngine.h
index 4801bde107..b4cc6f828a 100644
--- a/src/servers/app/GlyphLayoutEngine.h
+++ b/src/servers/app/GlyphLayoutEngine.h
@@ -16,6 +16,8 @@
 #include "FontManager.h"
 #include "ServerFont.h"
 
+#include <Debug.h>
+
 #include <ctype.h>
 
 class FontCacheReference {