diff --git a/test/run-tests.js b/test/run-tests.js
index 1d0de8ca..6d7f7244 100755
--- a/test/run-tests.js
+++ b/test/run-tests.js
@@ -104,6 +104,9 @@ function run_compress_tests() {
             }
             var output = input.transform(cmp);
             output.figure_out_scope();
+            if (test.mangle) {
+                output.mangle_names(test.mangle);
+            }
             output = make_code(output, false);
             if (expect != output) {
                 log("!!! failed\n---INPUT---\n{input}\n---OUTPUT---\n{output}\n---EXPECTED---\n{expected}\n\n", {