diff --git a/signal.c b/signal.c
index 54bb1760d3..f5900e66f8 100644
--- a/signal.c
+++ b/signal.c
@@ -905,6 +905,8 @@ sigbus(int sig SIGINFO_ARG)
 }
 #endif
 
+NORETURN(static void ruby_abort(void));
+
 static void
 ruby_abort(void)
 {