diff --git a/lib/6to5/transformation/transformers/es6-classes.js b/lib/6to5/transformation/transformers/es6-classes.js
index 063a91aaa4..18c2657ca3 100644
--- a/lib/6to5/transformation/transformers/es6-classes.js
+++ b/lib/6to5/transformation/transformers/es6-classes.js
@@ -141,11 +141,11 @@ Class.prototype.buildBody = function () {
   var staticProps;
 
   if (this.hasInstanceMutators) {
-    instanceProps = util.buildDefineProperties(this.instanceMutatorMap, true);
+    instanceProps = util.buildDefineProperties(this.instanceMutatorMap);
   }
 
   if (this.hasStaticMutators) {
-    staticProps = util.buildDefineProperties(this.staticMutatorMap, true);
+    staticProps = util.buildDefineProperties(this.staticMutatorMap);
   }
 
   if (instanceProps || staticProps) {
diff --git a/lib/6to5/util.js b/lib/6to5/util.js
index 659ec25ed5..d161eec184 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, writable) {
+exports.buildDefineProperties = function (mutatorMap) {
   var objExpr = t.objectExpression([]);
 
   _.each(mutatorMap, function (map) {
@@ -101,7 +101,10 @@ exports.buildDefineProperties = function (mutatorMap, writable) {
 
     var propNode = t.property("init", map._key, mapNode, map._computed);
 
-    if (writable) map.writable = t.literal(true);
+    if (!map.get && !map.set) {
+      map.writable = t.literal(true);
+    }
+
     map.enumerable = t.literal(true);
     map.configurable = t.literal(true);
 
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 e9b1e3b709..69617191a5 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 +16,6 @@ var Test = (function () {
       set: function (val) {
         this._test = val;
       },
-      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 af576011f1..997a39bcd9 100644
--- a/test/fixtures/transformation/es6-classes/instance-getter/expected.js
+++ b/test/fixtures/transformation/es6-classes/instance-getter/expected.js
@@ -13,7 +13,6 @@ var Test = (function () {
       get: function () {
         return 5 + 5;
       },
-      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 d713ba3a2c..96f0db0ad7 100644
--- a/test/fixtures/transformation/es6-classes/instance-setter/expected.js
+++ b/test/fixtures/transformation/es6-classes/instance-setter/expected.js
@@ -13,7 +13,6 @@ var Test = (function () {
       set: function (val) {
         this._test = val;
       },
-      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 7f0b2e0806..6f1deec853 100644
--- a/test/fixtures/transformation/es6-classes/static/expected.js
+++ b/test/fixtures/transformation/es6-classes/static/expected.js
@@ -14,7 +14,6 @@ var A = (function () {
     b: {
       get: function () {},
       set: function (b) {},
-      writable: 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 8b6a42a193..a581ab4d3a 100644
--- a/test/fixtures/transformation/playground/object-getter-memoization/expected.js
+++ b/test/fixtures/transformation/playground/object-getter-memoization/expected.js
@@ -22,7 +22,6 @@ var Foo = (function () {
       get: function () {
         return _defineProperty(this, "bar", complex()).bar;
       },
-      writable: true,
       enumerable: true,
       configurable: true
     }
@@ -30,7 +29,6 @@ var Foo = (function () {
     get: function () {
       return _defineProperty(this, bar, complex())[bar];
     },
-    writable: 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 ced471078f..71d586257e 100644
--- a/test/fixtures/transformation/source-maps/class/expected.js
+++ b/test/fixtures/transformation/source-maps/class/expected.js
@@ -13,7 +13,6 @@ var Test = (function () {
       get: function () {
         throw new Error("wow");
       },
-      writable: true,
       enumerable: true,
       configurable: true
     }