diff --git a/aws-iot-device-sdk-python-master/AWSIoTPythonSDK/core/protocol/paho/client.py b/aws-iot-device-sdk-python-master/AWSIoTPythonSDK/core/protocol/paho/client.py
index 503d1c6..f68676c 100755
--- a/aws-iot-device-sdk-python-master/AWSIoTPythonSDK/core/protocol/paho/client.py
+++ b/aws-iot-device-sdk-python-master/AWSIoTPythonSDK/core/protocol/paho/client.py
@@ -940,7 +940,7 @@ def publish(self, topic, payload=None, qos=0, retain=False):
         A ValueError will be raised if topic is None, has zero length or is
         invalid (contains a wildcard), if qos is not one of 0, 1 or 2, or if
         the length of the payload is greater than 268435455 bytes."""
-        if topic is None or len(topic) == 0:
+        if topic is None or not topic:
             raise ValueError('Invalid topic.')
         if qos<0 or qos>2:
             raise ValueError('Invalid QoS level.')