diff --git a/LibC/sys/cdefs.h b/LibC/sys/cdefs.h
index 8f05740393..1b6b52cca2 100644
--- a/LibC/sys/cdefs.h
+++ b/LibC/sys/cdefs.h
@@ -2,7 +2,9 @@
 
 #define _POSIX_VERSION 200809L
 
+#ifndef ALWAYS_INLINE
 #define ALWAYS_INLINE inline __attribute__((always_inline))
+#endif
 
 #ifdef __cplusplus
 #    define __BEGIN_DECLS extern "C" {