diff --git a/tempest/lib/common/rest_client.py b/tempest/lib/common/rest_client.py
index 4e851b0..229d179 100644
--- a/tempest/lib/common/rest_client.py
+++ b/tempest/lib/common/rest_client.py
@@ -895,11 +895,11 @@
                                         cls=JSONSCHEMA_VALIDATOR,
                                         format_checker=FORMAT_CHECKER)
                 except jsonschema.ValidationError as ex:
-                    msg = ("HTTP response body is invalid (%s)") % ex
+                    msg = ("HTTP response body is invalid (%s)" % ex)
                     raise exceptions.InvalidHTTPResponseBody(msg)
             else:
                 if body:
-                    msg = ("HTTP response body should not exist (%s)") % body
+                    msg = ("HTTP response body should not exist (%s)" % body)
                     raise exceptions.InvalidHTTPResponseBody(msg)
 
             # Check the header of a response
@@ -910,7 +910,7 @@
                                         cls=JSONSCHEMA_VALIDATOR,
                                         format_checker=FORMAT_CHECKER)
                 except jsonschema.ValidationError as ex:
-                    msg = ("HTTP response header is invalid (%s)") % ex
+                    msg = ("HTTP response header is invalid (%s)" % ex)
                     raise exceptions.InvalidHTTPResponseHeader(msg)