diff --git a/httpx/_client.py b/httpx/_client.py
index 021128d5..5bfa4c6c 100644
--- a/httpx/_client.py
+++ b/httpx/_client.py
@@ -370,7 +370,7 @@ class BaseClient:
         if merge_url.is_relative_url:
             # To merge URLs we always append to the base URL. To get this
             # behaviour correct we always ensure the base URL ends in a '/'
-            # seperator, and strip any leading '/' from the merge URL.
+            # separator, and strip any leading '/' from the merge URL.
             #
             # So, eg...
             #