diff --git a/test/unittest/regextest.cpp b/test/unittest/regextest.cpp
index cdd3630..cf89973 100644
--- a/test/unittest/regextest.cpp
+++ b/test/unittest/regextest.cpp
@@ -595,6 +595,7 @@ TEST(Regex, Invalid) {
     TEST_INVALID("");
     TEST_INVALID("a|");
     TEST_INVALID("()");
+    TEST_INVALID("(");
     TEST_INVALID(")");
     TEST_INVALID("(a))");
     TEST_INVALID("(a|)");