diff --git a/reactos/lib/user32/include/user32.h b/reactos/lib/user32/include/user32.h
index 33c413a3bed..69fb884106a 100644
--- a/reactos/lib/user32/include/user32.h
+++ b/reactos/lib/user32/include/user32.h
@@ -11,6 +11,10 @@
 #ifndef USER32_H
 #define USER32_H
 
+/* C Headers */
+#include <stdio.h>
+#include <ctype.h>
+
 /* SDK/NDK Headers */
 #include <windows.h>
 #include <windowsx.h>