diff --git a/tempest/lib/common/api_version_utils.py b/tempest/lib/common/api_version_utils.py
index 709c319..d29362d 100644
--- a/tempest/lib/common/api_version_utils.py
+++ b/tempest/lib/common/api_version_utils.py
@@ -12,6 +12,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import six
 import testtools
 
 from tempest.lib.common import api_version_request
@@ -108,10 +109,12 @@
 
     :param api_microversion_header_name: Microversion header name
             Example- "X-OpenStack-Nova-API-Version"
-    :param api_microversion: Microversion number like "2.10"
+    :param api_microversion: Microversion number like "2.10", type str.
     :param response_header: Response header where microversion is
             expected to be present.
     """
+    if not isinstance(api_microversion, six.string_types):
+        raise TypeError('api_microversion must be a string')
     api_microversion_header_name = api_microversion_header_name.lower()
     if (api_microversion_header_name not in response_header or
         api_microversion != response_header[api_microversion_header_name]):