diff --git a/javascript/ql/test/library-tests/TaintTracking/tst.js b/javascript/ql/test/library-tests/TaintTracking/tst.js
index c69895625cad..d268c02e687b 100644
--- a/javascript/ql/test/library-tests/TaintTracking/tst.js
+++ b/javascript/ql/test/library-tests/TaintTracking/tst.js
@@ -71,4 +71,5 @@ function test() {
 
     sink(Map.groupBy(x, z => z)); // NOT OK
     sink(Custom.groupBy(x, z => z)); // OK
+    sink(Object.groupBy(x, z => z)); // NOT OK -- This should be marked via taint step, but it is not.
 }