diff --git a/krl-mode.el b/krl-mode.el
index b08ade0..ccd974d 100644
--- a/krl-mode.el
+++ b/krl-mode.el
@@ -89,6 +89,7 @@
     "RETURN"
     "STRUC"
     "TO"
+    "SIGNAL"
     ))
 
 (defconst krl-keywords