diff --git a/lib/6to5/transformation/transformers/es6-classes.js b/lib/6to5/transformation/transformers/es6-classes.js
index c6ea9505de..01c1ee0729 100644
--- a/lib/6to5/transformation/transformers/es6-classes.js
+++ b/lib/6to5/transformation/transformers/es6-classes.js
@@ -145,11 +145,11 @@ Class.prototype.buildBody = function () {
       CLASS_NAME: className
     });
 
-    instanceProps = util.buildDefineProperties(this.instanceMutatorMap, protoId);
+    instanceProps = util.buildDefineProperties(this.instanceMutatorMap, true);
   }
 
   if (this.hasStaticMutators) {
-    staticProps = util.buildDefineProperties(this.staticMutatorMap, className);
+    staticProps = util.buildDefineProperties(this.staticMutatorMap, true);
   }
 
   if (instanceProps || staticProps) {
diff --git a/lib/6to5/util.js b/lib/6to5/util.js
index e96d638d21..659ec25ed5 100644
--- a/lib/6to5/util.js
+++ b/lib/6to5/util.js
@@ -93,7 +93,7 @@ exports.pushMutatorMap = function (mutatorMap, key, kind, computed, method) {
   map[kind] = method;
 };
 
-exports.buildDefineProperties = function (mutatorMap) {
+exports.buildDefineProperties = function (mutatorMap, writable) {
   var objExpr = t.objectExpression([]);
 
   _.each(mutatorMap, function (map) {
@@ -101,7 +101,9 @@ exports.buildDefineProperties = function (mutatorMap) {
 
     var propNode = t.property("init", map._key, mapNode, map._computed);
 
+    if (writable) map.writable = t.literal(true);
     map.enumerable = t.literal(true);
+    map.configurable = t.literal(true);
 
     _.each(map, function (node, key) {
       if (key[0] === "_") return;
diff --git a/test/fixtures/transformation/es6-classes/instance-getter-and-setter/expected.js b/test/fixtures/transformation/es6-classes/instance-getter-and-setter/expected.js
index 6d90b4abd4..e9b1e3b709 100644
--- a/test/fixtures/transformation/es6-classes/instance-getter-and-setter/expected.js
+++ b/test/fixtures/transformation/es6-classes/instance-getter-and-setter/expected.js
@@ -16,7 +16,9 @@ var Test = (function () {
       set: function (val) {
         this._test = val;
       },
-      enumerable: true
+      writable: true,
+      enumerable: true,
+      configurable: true
     }
   });
 
diff --git a/test/fixtures/transformation/es6-classes/instance-getter/expected.js b/test/fixtures/transformation/es6-classes/instance-getter/expected.js
index 10922e7805..af576011f1 100644
--- a/test/fixtures/transformation/es6-classes/instance-getter/expected.js
+++ b/test/fixtures/transformation/es6-classes/instance-getter/expected.js
@@ -13,7 +13,9 @@ var Test = (function () {
       get: function () {
         return 5 + 5;
       },
-      enumerable: true
+      writable: true,
+      enumerable: true,
+      configurable: true
     }
   });
 
diff --git a/test/fixtures/transformation/es6-classes/instance-setter/expected.js b/test/fixtures/transformation/es6-classes/instance-setter/expected.js
index 0fb2a379ef..d713ba3a2c 100644
--- a/test/fixtures/transformation/es6-classes/instance-setter/expected.js
+++ b/test/fixtures/transformation/es6-classes/instance-setter/expected.js
@@ -13,7 +13,9 @@ var Test = (function () {
       set: function (val) {
         this._test = val;
       },
-      enumerable: true
+      writable: true,
+      enumerable: true,
+      configurable: true
     }
   });
 
diff --git a/test/fixtures/transformation/es6-classes/static/expected.js b/test/fixtures/transformation/es6-classes/static/expected.js
index 59c3cfd171..7f0b2e0806 100644
--- a/test/fixtures/transformation/es6-classes/static/expected.js
+++ b/test/fixtures/transformation/es6-classes/static/expected.js
@@ -14,7 +14,9 @@ var A = (function () {
     b: {
       get: function () {},
       set: function (b) {},
-      enumerable: true
+      writable: true,
+      enumerable: true,
+      configurable: true
     }
   });
 
diff --git a/test/fixtures/transformation/es6-property-method-assignment/computed/expected.js b/test/fixtures/transformation/es6-property-method-assignment/computed/expected.js
index 5622ed391e..aa6f306654 100644
--- a/test/fixtures/transformation/es6-property-method-assignment/computed/expected.js
+++ b/test/fixtures/transformation/es6-property-method-assignment/computed/expected.js
@@ -18,7 +18,8 @@ var obj = Object.defineProperties({}, _defineProperty({}, x, {
   set: function (value) {
     valueSet = value;
   },
-  enumerable: true
+  enumerable: true,
+  configurable: true
 }));
 obj.y = "foo";
 obj.y === 1 && valueSet === "foo";
diff --git a/test/fixtures/transformation/es6-property-method-assignment/getter-and-setter/expected.js b/test/fixtures/transformation/es6-property-method-assignment/getter-and-setter/expected.js
index a15cb74461..036772d3c9 100644
--- a/test/fixtures/transformation/es6-property-method-assignment/getter-and-setter/expected.js
+++ b/test/fixtures/transformation/es6-property-method-assignment/getter-and-setter/expected.js
@@ -8,6 +8,7 @@ var obj = Object.defineProperties({}, {
     set: function (value) {
       this._foo = value;
     },
-    enumerable: true
+    enumerable: true,
+    configurable: true
   }
 });
diff --git a/test/fixtures/transformation/es6-property-method-assignment/getter/expected.js b/test/fixtures/transformation/es6-property-method-assignment/getter/expected.js
index 41284a6062..7e898ee4a1 100644
--- a/test/fixtures/transformation/es6-property-method-assignment/getter/expected.js
+++ b/test/fixtures/transformation/es6-property-method-assignment/getter/expected.js
@@ -5,6 +5,7 @@ var obj = Object.defineProperties({}, {
     get: function () {
       return 5 + 5;
     },
-    enumerable: true
+    enumerable: true,
+    configurable: true
   }
 });
diff --git a/test/fixtures/transformation/es6-property-method-assignment/setter/expected.js b/test/fixtures/transformation/es6-property-method-assignment/setter/expected.js
index dd3cb8477f..a04867b4aa 100644
--- a/test/fixtures/transformation/es6-property-method-assignment/setter/expected.js
+++ b/test/fixtures/transformation/es6-property-method-assignment/setter/expected.js
@@ -5,6 +5,7 @@ var obj = Object.defineProperties({}, {
     set: function (value) {
       this._foo = value;
     },
-    enumerable: true
+    enumerable: true,
+    configurable: true
   }
 });
diff --git a/test/fixtures/transformation/playground/object-getter-memoization/expected.js b/test/fixtures/transformation/playground/object-getter-memoization/expected.js
index ac43f9b05d..8b6a42a193 100644
--- a/test/fixtures/transformation/playground/object-getter-memoization/expected.js
+++ b/test/fixtures/transformation/playground/object-getter-memoization/expected.js
@@ -22,13 +22,17 @@ var Foo = (function () {
       get: function () {
         return _defineProperty(this, "bar", complex()).bar;
       },
-      enumerable: true
+      writable: true,
+      enumerable: true,
+      configurable: true
     }
   }, bar, {
     get: function () {
       return _defineProperty(this, bar, complex())[bar];
     },
-    enumerable: true
+    writable: true,
+    enumerable: true,
+    configurable: true
   }));
 
   return Foo;
@@ -39,11 +43,13 @@ var foo = Object.defineProperties({}, _defineProperty({
     get: function () {
       return _defineProperty(this, "bar", complex()).bar;
     },
-    enumerable: true
+    enumerable: true,
+    configurable: true
   }
 }, bar, {
   get: function () {
     return _defineProperty(this, bar, complex())[bar];
   },
-  enumerable: true
+  enumerable: true,
+  configurable: true
 }));
diff --git a/test/fixtures/transformation/source-maps/class/expected.js b/test/fixtures/transformation/source-maps/class/expected.js
index 43d698e530..ced471078f 100644
--- a/test/fixtures/transformation/source-maps/class/expected.js
+++ b/test/fixtures/transformation/source-maps/class/expected.js
@@ -13,7 +13,9 @@ var Test = (function () {
       get: function () {
         throw new Error("wow");
       },
-      enumerable: true
+      writable: true,
+      enumerable: true,
+      configurable: true
     }
   });