diff --git a/homeassistant/components/mqtt/__init__.py b/homeassistant/components/mqtt/__init__.py
index e86d1314b5a..d05ec1f5453 100644
--- a/homeassistant/components/mqtt/__init__.py
+++ b/homeassistant/components/mqtt/__init__.py
@@ -70,9 +70,10 @@ MQTT_PUBLISH_SCHEMA = vol.Schema({
     vol.Required(ATTR_TOPIC): mqtt_topic,
     vol.Exclusive(ATTR_PAYLOAD, 'payload'): object,
     vol.Exclusive(ATTR_PAYLOAD_TEMPLATE, 'payload'): cv.string,
-    vol.Required(ATTR_QOS, default=DEFAULT_QOS): vol.In([0, 1, 2]),
-    vol.Required(ATTR_RETAIN, default=DEFAULT_RETAIN): vol.Coerce(bool),
-})
+    vol.Required(ATTR_QOS, default=DEFAULT_QOS):
+        vol.All(vol.Coerce(int), vol.In([0, 1, 2])),
+    vol.Required(ATTR_RETAIN, default=DEFAULT_RETAIN): vol.Boolean(),
+}, required=True)
 
 
 def _build_publish_data(topic, qos, retain):
@@ -194,7 +195,8 @@ def setup(hass, config):
         qos = call.data[ATTR_QOS]
         retain = call.data[ATTR_RETAIN]
         try:
-            payload = payload or template.render(hass, payload_template)
+            payload = (payload if payload_template is None else
+                       template.render(hass, payload_template)) or ''
         except template.jinja2.TemplateError as exc:
             _LOGGER.error(
                 "Unable to publish to '%s': rendering payload template of "
diff --git a/tests/components/mqtt/test_init.py b/tests/components/mqtt/test_init.py
index 04f5f574413..d57504562c1 100644
--- a/tests/components/mqtt/test_init.py
+++ b/tests/components/mqtt/test_init.py
@@ -104,14 +104,31 @@ class TestMQTT(unittest.TestCase):
     def test_service_call_without_payload_or_payload_template(self):
         """Test the service call without payload or payload template.
 
-        If neither 'payload' or 'payload_template' is provided then fail.
+        Send empty message if neither 'payload' nor 'payload_template'
+        are provided.
         """
         # Call the service directly because the helper functions require you to
         # provide a payload.
         self.hass.services.call(mqtt.DOMAIN, mqtt.SERVICE_PUBLISH, {
             mqtt.ATTR_TOPIC: "test/topic"
         }, blocking=True)
-        self.assertFalse(mqtt.MQTT_CLIENT.publish.called)
+        self.assertTrue(mqtt.MQTT_CLIENT.publish.called)
+        self.assertEqual(mqtt.MQTT_CLIENT.publish.call_args[0][1], "")
+
+    def test_service_call_with_ascii_qos_retain_flags(self):
+        """Test the service call with args that can be misinterpreted.
+
+        Empty payload message and ascii formatted qos and retain flags.
+        """
+        self.hass.services.call(mqtt.DOMAIN, mqtt.SERVICE_PUBLISH, {
+            mqtt.ATTR_TOPIC: "test/topic",
+            mqtt.ATTR_PAYLOAD: "",
+            mqtt.ATTR_QOS: '2',
+            mqtt.ATTR_RETAIN: 'no'
+        }, blocking=True)
+        self.assertTrue(mqtt.MQTT_CLIENT.publish.called)
+        self.assertEqual(mqtt.MQTT_CLIENT.publish.call_args[0][2], 2)
+        self.assertFalse(mqtt.MQTT_CLIENT.publish.call_args[0][3])
 
     def test_subscribe_topic(self):
         """Test the subscription of a topic."""