diff --git a/SC3015.md b/SC3015.md
index 6251ad5..74b0847 100644
--- a/SC3015.md
+++ b/SC3015.md
@@ -13,7 +13,8 @@ fi
 
 ```sh
 #!/bin/sh
-if expr "$var" : '.*foo[0-9]\{1,\}' >/dev/null; then
+# Use the x-hack to handle strings like '('.
+if expr "X$var" : 'X.*foo[0-9]\{1,\}' >/dev/null; then
   echo matched
 fi
 ```