diff --git a/js/src/builtin/MapObject.cpp b/js/src/builtin/MapObject.cpp
index 3e864ed5404..d9bd66b85f1 100644
--- a/js/src/builtin/MapObject.cpp
+++ b/js/src/builtin/MapObject.cpp
@@ -286,7 +286,7 @@ MapObject::construct(JSContext *cx, unsigned argc, Value *vp)
 JSBool
 MapObject::size(JSContext *cx, unsigned argc, Value *vp)
 {
-    THIS_MAP(get, cx, argc, vp, args, map);
+    THIS_MAP(size, cx, argc, vp, args, map);
     JS_STATIC_ASSERT(sizeof map.count() <= sizeof(uint32_t));
     args.rval().setNumber(map.count());
     return true;
@@ -455,7 +455,7 @@ SetObject::construct(JSContext *cx, unsigned argc, Value *vp)
 JSBool
 SetObject::size(JSContext *cx, unsigned argc, Value *vp)
 {
-    THIS_SET(has, cx, argc, vp, args, set);
+    THIS_SET(size, cx, argc, vp, args, set);
     JS_STATIC_ASSERT(sizeof set.count() <= sizeof(uint32_t));
     args.rval().setNumber(set.count());
     return true;
diff --git a/js/src/jit-test/tests/collections/bug-743101.js b/js/src/jit-test/tests/collections/bug-743101.js
new file mode 100644
index 00000000000..d30f3fc4e03
--- /dev/null
+++ b/js/src/jit-test/tests/collections/bug-743101.js
@@ -0,0 +1,5 @@
+load(libdir + "asserts.js");
+
+var g = newGlobal('new-compartment');
+assertThrowsInstanceOf(function () { Map.prototype.size.apply(g, []); }, g.TypeError);
+assertThrowsInstanceOf(function () { Set.prototype.size.apply(g, []); }, g.TypeError);