diff --git a/libc/include/sys/cdefs.h b/libc/include/sys/cdefs.h
index c7fb9de..a4c1aff 100644
--- a/libc/include/sys/cdefs.h
+++ b/libc/include/sys/cdefs.h
@@ -211,8 +211,10 @@
 #define __statement(x)	(x)
 #endif
 
-#define __printflike(x, y) __attribute__((__format__(printf, x, y))) __attribute__((__nonnull__(x)))
-#define __scanflike(x, y) __attribute__((__format__(scanf, x, y))) __attribute__((__nonnull__(x)))
+#define __nonnull(args) __attribute__((__nonnull__ args))
+
+#define __printflike(x, y) __attribute__((__format__(printf, x, y))) __nonnull((x))
+#define __scanflike(x, y) __attribute__((__format__(scanf, x, y))) __nonnull((x))
 
 /*
  * C99 defines the restrict type qualifier keyword, which was made available