diff --git a/t/t4018-diff-funcname.sh b/t/t4018-diff-funcname.sh
index be541348c6f8d469428e2fcc7abaf6d25168c08f..5b10e976a3fd0c554ff2fa14004e69343a9ec634 100755
--- a/t/t4018-diff-funcname.sh
+++ b/t/t4018-diff-funcname.sh
@@ -32,7 +32,7 @@ EOF
 
 sed 's/beer\\/beer,\\/' < Beer.java > Beer-correct.java
 
-builtin_patterns="bibtex html java objc pascal php python ruby tex"
+builtin_patterns="bibtex cpp html java objc pascal php python ruby tex"
 for p in $builtin_patterns
 do
 	test_expect_success "builtin $p pattern compiles" '