diff --git a/linux-user/signal.c b/linux-user/signal.c
index 8ee5c4b..1e29c2c 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -422,7 +422,7 @@
     struct sigaction act1;
     int host_sig;
 
-    if (sig < 1 || sig > TARGET_NSIG)
+    if (sig < 1 || sig > TARGET_NSIG || sig == SIGKILL || sig == SIGSTOP)
         return -EINVAL;
     k = &sigact_table[sig - 1];
 #if defined(DEBUG_SIGNAL)