diff --git a/SC2172.md b/SC2172.md
index 1457245..12ce891 100644
--- a/SC2172.md
+++ b/SC2172.md
@@ -1,4 +1,4 @@
-## Trapping signals by number is not well defined. Prefer signal names.
+## Trapping signals by number is not well-defined. Prefer signal names.
 
 ### Problematic code: