diff --git a/lib/common/util.js b/lib/common/util.js
index d75de15747d..da91181546c 100644
--- a/lib/common/util.js
+++ b/lib/common/util.js
@@ -245,9 +245,7 @@ function getType(value) {
  */
 function prop(name) {
   return function(item) {
-    if (name in item) {
-      return item[name];
-    }
+    return item[name];
   };
 }
 
diff --git a/lib/pubsub/topic.js b/lib/pubsub/topic.js
index 606d72654bf..2479cf791cb 100644
--- a/lib/pubsub/topic.js
+++ b/lib/pubsub/topic.js
@@ -87,7 +87,7 @@ Topic.formatMessage_ = function(message) {
 
 /**
  * Format the name of a topic. A Topic's full name is in the format of
- * 'projects/{projectId}/topics/{topicName}.
+ * 'projects/{projectId}/topics/{topicName}'.
  *
  * @private
  *
@@ -102,8 +102,8 @@ Topic.formatName_ = function(projectId, name) {
 };
 
 /**
- * Wrapper for makeReq_ that automatically attempts to create a topic if it
- * does not yet exist.
+ * Wrapper for makeReq_ that automatically attempts to create a topic if it does
+ * not yet exist.
  *
  * @private
  */
@@ -130,10 +130,11 @@ Topic.prototype.autoCreateWrapper_ = function(method, path, q, body, callback) {
 };
 
 /**
- * Publish the provided message or array of messages. A message can be of any
- * type. On success, an array of messageIds is returned in the response.
+ * Publish the provided message or array of messages. On success, an array of
+ * messageIds is returned in the response.
  *
  * @throws {Error} If no message is provided.
+ * @throws {Error} If a message is missing a data property.
  *
  * @param {object|object[]} message - The message(s) to publish.
  * @param {*} message.data - The contents of the message.
@@ -178,6 +179,10 @@ Topic.prototype.publish = function(messages, callback) {
     throw new Error('Cannot publish without a message.');
   }
 
+  if (!messages.every(util.prop('data'))) {
+    throw new Error('Cannot publish message without a `data` property.');
+  }
+
   callback = callback || util.noop;
 
   var body = {
diff --git a/test/pubsub/topic.js b/test/pubsub/topic.js
index 284b1875a5e..9f281f0dd4f 100644
--- a/test/pubsub/topic.js
+++ b/test/pubsub/topic.js
@@ -129,11 +129,17 @@ describe('Topic', function() {
     it('should throw if no message is provided', function() {
       assert.throws(function() {
         topic.publish();
-      }, /Cannot publish/);
+      }, /Cannot publish without a message/);
 
       assert.throws(function() {
         topic.publish([]);
-      }, /Cannot publish/);
+      }, /Cannot publish without a message/);
+    });
+
+    it('should throw if a message has no data', function() {
+      assert.throws(function() {
+        topic.publish(message);
+      }, /Cannot publish message without a `data` property/);
     });
 
     it('should send correct api request', function(done) {