1 files changed, 1 insertions, 1 deletions
diff --git a/lib/compress.js b/lib/compress.js
index 81b9ccac..5f2ac2b0 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1419,7 +1419,7 @@ merge(Compressor.prototype, {
             });
             if (value && typeof value == "object") {
                 var props = [];
-                for (var key in value) {
+                for (var key in value) if (HOP(value, key)) {
                     props.push(make_node(AST_ObjectKeyVal, orig, {
                         key: key,
                         value: to_node(value[key], orig)