Index: src/runtime/ObjFW-RT.h
==================================================================
--- src/runtime/ObjFW-RT.h
+++ src/runtime/ObjFW-RT.h
@@ -41,10 +41,13 @@
 #  define _Nonnull
 # endif
 # ifndef _Nullable
 #  define _Nullable
 # endif
+# ifndef _Null_unspecified
+#  define _Null_unspecified
+# endif
 #endif
 
 #if !__has_feature(objc_arc) && !defined(__unsafe_unretained)
 # define __unsafe_unretained
 #endif