diff --git a/libc/include/signal.h b/libc/include/signal.h
index 8d9d63f..085f92f 100644
--- a/libc/include/signal.h
+++ b/libc/include/signal.h
@@ -115,15 +115,18 @@
 
 int sigaction(int, const struct sigaction*, struct sigaction*);
 
-__BIONIC_LEGACY_INLINE sighandler_t signal(int, sighandler_t);
-
 int siginterrupt(int, int);
 
-__BIONIC_LEGACY_INLINE int sigaddset(sigset_t* _Nonnull, int);
-__BIONIC_LEGACY_INLINE int sigdelset(sigset_t* _Nonnull, int);
-__BIONIC_LEGACY_INLINE int sigemptyset(sigset_t* _Nonnull);
-__BIONIC_LEGACY_INLINE int sigfillset(sigset_t* _Nonnull);
-__BIONIC_LEGACY_INLINE int sigismember(const sigset_t* _Nonnull, int);
+#if __ANDROID_API__ >= 21
+sighandler_t signal(int, sighandler_t);
+int sigaddset(sigset_t*, int);
+int sigdelset(sigset_t*, int);
+int sigemptyset(sigset_t*);
+int sigfillset(sigset_t*);
+int sigismember(const sigset_t*, int);
+#else
+// Implemented as static inlines before 21.
+#endif
 
 int sigpending(sigset_t* _Nonnull);
 int sigprocmask(int, const sigset_t*, sigset_t*);