diff --git a/lib/pubsub/index.js b/lib/pubsub/index.js
index 2079b143044..727c473da01 100644
--- a/lib/pubsub/index.js
+++ b/lib/pubsub/index.js
@@ -42,7 +42,7 @@ var util = require('../common/util.js');
  * @const {string} Base URL for Pub/Sub API.
  * @private
  */
-var PUBSUB_BASE_URL = 'https://pubsub.googleapis.com/v1beta2/';
+var PUBSUB_BASE_URL = 'https://pubsub.googleapis.com/v1/';
 
 /**
  * @const {array} Required scopes for Pub/Sub API.
diff --git a/lib/pubsub/subscription.js b/lib/pubsub/subscription.js
index 87fc6ef8335..ca6b8ea6b59 100644
--- a/lib/pubsub/subscription.js
+++ b/lib/pubsub/subscription.js
@@ -387,7 +387,7 @@ Subscription.prototype.pull = function(options, callback) {
  * interrupted.
  *
  * @param {object} options - The configuration object.
- * @param {number} options.ackId - The ack id to change.
+ * @param {number|number[]} options.ackIds - The ack id(s) to change.
  * @param {number} options.seconds - Number of seconds after call is made to
  *     set the deadline of the ack.
  * @param {Function=} callback - The callback function.
@@ -401,7 +401,7 @@ Subscription.prototype.pull = function(options, callback) {
  */
 Subscription.prototype.setAckDeadline = function(options, callback) {
   var body = {
-    ackId: options.ackId,
+    ackIds: util.arrayize(options.ackIds),
     ackDeadlineSeconds: options.seconds
   };
 
diff --git a/system-test/pubsub.js b/system-test/pubsub.js
index 82c6a55b3d8..7389723bbb6 100644
--- a/system-test/pubsub.js
+++ b/system-test/pubsub.js
@@ -238,7 +238,7 @@ describe('pubsub', function() {
           assert.ifError(err);
 
           var options = {
-            ackId: msgs[0].ackId,
+            ackIds: [msgs[0].ackId],
             seconds: 10
           };
           subscription.setAckDeadline(options, done);
diff --git a/test/pubsub/subscription.js b/test/pubsub/subscription.js
index df66e2648ef..b5b710abf93 100644
--- a/test/pubsub/subscription.js
+++ b/test/pubsub/subscription.js
@@ -554,10 +554,10 @@ describe('Subscription', function() {
         assert.equal(method, 'POST');
         assert.equal(path, this.name + ':modifyAckDeadline');
         assert.equal(qs, null);
-        assert.deepEqual(body, { ackId: 123, ackDeadlineSeconds: 10 });
+        assert.deepEqual(body, { ackIds: [123], ackDeadlineSeconds: 10 });
         done();
       };
-      subscription.setAckDeadline({ ackId: 123, seconds: 10 }, done);
+      subscription.setAckDeadline({ ackIds: [123], seconds: 10 }, done);
     });
 
     it('should execute the callback', function(done) {