@@ -6,10 +6,15 @@
  *
  * This file is part of libobjfw. It may be distributed under the terms of the
  * Q Public License 1.0, which can be found in the file LICENSE included in
  * the packaging of this file.
  */
+
+#ifndef OF_CONFIGURED
+#error You are missing the libobjfw definitions!
+#error Please use objfw-config!
+#endif
 
 #include <stddef.h>
 #include <stdint.h>
 
 #import <objc/objc.h>