diff --git a/HISTORY.rst b/HISTORY.rst
index 289c87a00..d0237e16c 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -3,6 +3,13 @@
 Release History
 ===============
 
+0.10.9
++++++++++++++++
+
+**Azure IoT Product Certification service**
+
+* Fix bug for `az iot product test create` sending a byte string instead of "regular" base64 string.
+
 0.10.8
 +++++++++++++++
 
diff --git a/azext_iot/constants.py b/azext_iot/constants.py
index 4e30e223b..8b8f419db 100644
--- a/azext_iot/constants.py
+++ b/azext_iot/constants.py
@@ -7,7 +7,7 @@
 
 import os
 
-VERSION = "0.10.8"
+VERSION = "0.10.9"
 EXTENSION_NAME = "azure-iot"
 EXTENSION_ROOT = os.path.dirname(os.path.abspath(__file__))
 EXTENSION_CONFIG_ROOT_KEY = "iotext"
diff --git a/azext_iot/product/test/command_tests.py b/azext_iot/product/test/command_tests.py
index 7d73a351c..3e5cb9948 100644
--- a/azext_iot/product/test/command_tests.py
+++ b/azext_iot/product/test/command_tests.py
@@ -278,9 +278,8 @@ def _read_certificate_from_file(certificate_path):
     with open(file=certificate_path, mode="rb") as f:
         data = f.read()
 
-        from base64 import encodestring  # pylint: disable=no-name-in-module
-
-        return encodestring(data)
+        from base64 import b64encode  # pylint: disable=no-name-in-module
+        return b64encode(data).decode('utf-8')
 
 
 def _create_from_file(configuration_file):