diff --git a/test/scripts/mustfail/string-concat.toy b/test/scripts/mustfail/string-concat.toy
new file mode 100644
index 0000000..d89ef41
--- /dev/null
+++ b/test/scripts/mustfail/string-concat.toy
@@ -0,0 +1,5 @@
+{
+	var s = "foo" - "bar";
+}
+
+print "All good";
diff --git a/test/test_mustfail.c b/test/test_mustfail.c
index 087bcf7..a937c8c 100644
--- a/test/test_mustfail.c
+++ b/test/test_mustfail.c
@@ -100,6 +100,7 @@ int main() {
 			"declare-types-dictionary-key.toy",
 			"declare-types-dictionary-value.toy",
 			"index-arrays-non-integer.toy",
+			"string-concat.toy",
 			"unary-inverted-nothing.toy",
 			"unary-negative-nothing.toy",
 			NULL