diff --git a/pkgs/development/interpreters/python/python-packages-base.nix b/pkgs/development/interpreters/python/python-packages-base.nix
index c513561ce6fb..dfb19b651285 100644
--- a/pkgs/development/interpreters/python/python-packages-base.nix
+++ b/pkgs/development/interpreters/python/python-packages-base.nix
@@ -23,7 +23,11 @@ let
       origArgs:
       let
         result = f origArgs;
-        overrideWith = newArgs: origArgs // lib.toFunction newArgs origArgs;
+        overrideWith =
+          if lib.isFunction origArgs then
+            newArgs: lib.extends (_: lib.toFunction newArgs) origArgs
+          else
+            newArgs: origArgs // lib.toFunction newArgs origArgs;
       in
       if lib.isAttrs result then
         result