diff --git a/zulip/zulip/__init__.py b/zulip/zulip/__init__.py
index 40b7a954..a013d8c5 100644
--- a/zulip/zulip/__init__.py
+++ b/zulip/zulip/__init__.py
@@ -585,7 +585,7 @@ class Client:
         req_files = []
 
         for key, val in orig_request.items():
-            if isinstance(val, str) or isinstance(val, str):
+            if isinstance(val, str):
                 request[key] = val
             else:
                 request[key] = json.dumps(val)