diff --git a/headers/posix/strings.h b/headers/posix/strings.h
index adc06074b4..5a70c862b5 100644
--- a/headers/posix/strings.h
+++ b/headers/posix/strings.h
@@ -13,7 +13,7 @@
 extern "C" {
 #endif
 
-static inline int ffs(int i) { return __builtin_ffs(i); }
+static __inline__ int ffs(int i) { return __builtin_ffs(i); }
 
 extern int		strcasecmp(const char *string1, const char *string2);
 extern int		strncasecmp(const char *string1, const char *string2,