diff --git a/newlib/libc/posix/posix_spawn.c b/newlib/libc/posix/posix_spawn.c
index 6fd6159d0..46e4e5369 100644
--- a/newlib/libc/posix/posix_spawn.c
+++ b/newlib/libc/posix/posix_spawn.c
@@ -199,6 +199,8 @@ process_spawnattr(const posix_spawnattr_t sa)
 
 	if (sa->sa_flags & POSIX_SPAWN_SETSIGDEF) {
 		for (i = 1; i < NSIG; i++) {
+			if (i == SIGKILL || i == SIGSTOP)
+				continue;
 			if (sigismember(&sa->sa_sigdefault, i))
 				if (sigaction(i, &sigact, NULL) != 0)
 					return (errno);