2 files changed, 20 insertions, 3 deletions
diff --git a/js/src/builtin/ModuleObject.cpp b/js/src/builtin/ModuleObject.cpp
index 28a3329a8..6d42508e0 100644
--- a/js/src/builtin/ModuleObject.cpp
+++ b/js/src/builtin/ModuleObject.cpp
@@ -500,7 +500,7 @@ ModuleNamespaceObject::ProxyHandler::ownPropertyKeys(JSContext* cx, HandleObject
     Rooted<ModuleNamespaceObject*> ns(cx, &proxy->as<ModuleNamespaceObject>());
     RootedObject exports(cx, &ns->exports());
     uint32_t count;
-    if (!GetLengthProperty(cx, exports, &count) || !props.reserve(props.length() + count))
+    if (!GetLengthProperty(cx, exports, &count) || !props.reserve(props.length() + count + 1))
         return false;
 
     Rooted<ValueVector> names(cx, ValueVector(cx));
@@ -510,6 +510,8 @@ ModuleNamespaceObject::ProxyHandler::ownPropertyKeys(JSContext* cx, HandleObject
     for (uint32_t i = 0; i < count; i++)
         props.infallibleAppend(AtomToId(&names[i].toString()->asAtom()));
 
+    props.infallibleAppend(SYMBOL_TO_JSID(cx->wellKnownSymbols().toStringTag));
+
     return true;
 }
 
diff --git a/js/src/jit-test/tests/modules/import-namespace.js b/js/src/jit-test/tests/modules/import-namespace.js
index 27d0193aa..2094c27fe 100644
--- a/js/src/jit-test/tests/modules/import-namespace.js
+++ b/js/src/jit-test/tests/modules/import-namespace.js
@@ -19,9 +19,19 @@ function testHasNames(names, expected) {
     });
 }
 
+function testEqualArrays(actual, expected) {
+	assertEq(Array.isArray(actual), true);
+	assertEq(Array.isArray(expected), true);
+    assertEq(actual.length, expected.length);
+    for (let i = 0; i < expected.length; i++) {
+    	assertEq(actual[i], expected[i]);
+    }
+}
+
 let a = moduleRepo['a'] = parseModule(
-    `export var a = 1;
-     export var b = 2;`
+    `// Reflection methods should return these exports alphabetically sorted.
+     export var b = 2;
+     export var a = 1;`
 );
 
 let b = moduleRepo['b'] = parseModule(
@@ -66,6 +76,11 @@ assertEq(typeof desc.get, "undefined");
 assertEq(typeof desc.set, "undefined");
 assertEq(Object.prototype.toString.call(ns), "[object Module]");
 
+// Test [[OwnPropertyKeys]] internal method.
+testEqualArrays(Reflect.ownKeys(ns), ["a", "b", Symbol.toStringTag]);
+testEqualArrays(Object.getOwnPropertyNames(ns), ["a", "b"]);
+testEqualArrays(Object.getOwnPropertySymbols(ns), [Symbol.toStringTag]);
+
 // Test cyclic namespace import and access in module evaluation.
 let c = moduleRepo['c'] =
     parseModule("export let c = 1; import * as ns from 'd'; let d = ns.d;");