diff --git a/libc/include/bits/posix_limits.h b/libc/include/bits/posix_limits.h
index 31016a8..0f17381 100644
--- a/libc/include/bits/posix_limits.h
+++ b/libc/include/bits/posix_limits.h
@@ -29,6 +29,7 @@
 #ifndef _BITS_POSIX_LIMITS_H_
 #define _BITS_POSIX_LIMITS_H_
 
+#include <sys/cdefs.h>
 
 /* Any constant values here other than -1 or 200809L are explicitly specified by POSIX.1-2008. */
 /* Keep it sorted. */