diff --git a/libc/include/strings.h b/libc/include/strings.h
index ba69c8d..ff6b925 100644
--- a/libc/include/strings.h
+++ b/libc/include/strings.h
@@ -53,6 +53,10 @@
 #define __BIONIC_STRINGS_INLINE static __inline
 #endif
 
+#undef ffs
+#undef ffsl
+#undef ffsll
+
 __BEGIN_DECLS
 
 /** Deprecated. Use memmove() instead. */