diff --git a/packages/pubsub/src/subscription.js b/packages/pubsub/src/subscription.js
index 6610e7ef814..91847efe974 100644
--- a/packages/pubsub/src/subscription.js
+++ b/packages/pubsub/src/subscription.js
@@ -347,7 +347,7 @@ modelo.inherits(Subscription, commonGrpc.ServiceObject, events.EventEmitter);
  *
  * @private
  */
-Subscription.formatMessage_ = function(msg, encoding) {
+Subscription.formatMessage_ = function(msg, enc) {
   var innerMessage = msg.message;
   var message = {
     ackId: msg.ackId
@@ -357,11 +357,16 @@ Subscription.formatMessage_ = function(msg, encoding) {
     message.id = innerMessage.messageId;
 
     if (innerMessage.data) {
-      message.data = new Buffer(innerMessage.data, 'base64').toString(encoding);
+      if (enc === 'base64') {
+        // Prevent decoding and then re-encoding to base64.
+        message.data = innerMessage.data;
+      } else {
+        message.data = Buffer.from(innerMessage.data, 'base64').toString(enc);
 
-      try {
-        message.data = JSON.parse(message.data);
-      } catch(e) {}
+        try {
+          message.data = JSON.parse(message.data);
+        } catch(e) {}
+      }
     }
 
     if (innerMessage.attributes) {
diff --git a/packages/pubsub/test/subscription.js b/packages/pubsub/test/subscription.js
index bb0f65b9b14..a84bc9b9c2d 100644
--- a/packages/pubsub/test/subscription.js
+++ b/packages/pubsub/test/subscription.js
@@ -77,6 +77,11 @@ describe('Subscription', function() {
     data: messageBinary,
     id: 7
   };
+  var expectedMessageAsBase64 = {
+    ackId: 'abc',
+    data: messageBuffer,
+    id: 7
+  };
 
   before(function() {
     Subscription = proxyquire('../src/subscription.js', {
@@ -342,6 +347,12 @@ describe('Subscription', function() {
       assert.deepEqual(msg, expectedMessage);
     });
 
+    it('should decode buffer to base64', function() {
+      var msg = Subscription
+        .formatMessage_(messageObj.receivedMessages[0], 'base64');
+      assert.deepEqual(msg, expectedMessageAsBase64);
+    });
+
     it('should decode buffer to specified encoding', function() {
       var msg = Subscription
         .formatMessage_(messageObj.receivedMessages[0], 'binary');