diff --git a/pkgs/development/python-modules/isort/default.nix b/pkgs/development/python-modules/isort/default.nix
index 979213f945b..6cc2570ab36 100644
--- a/pkgs/development/python-modules/isort/default.nix
+++ b/pkgs/development/python-modules/isort/default.nix
@@ -5,11 +5,11 @@ let
   testOpts = lib.concatMapStringsSep " " (t: "--deselect test_isort.py::${t}") skipTests;
 in buildPythonPackage rec {
   pname = "isort";
-  version = "4.3.20"; # Note 4.x is the last version that supports Python2
+  version = "4.3.21"; # Note 4.x is the last version that supports Python2
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "c40744b6bc5162bbb39c1257fe298b7a393861d50978b565f3ccd9cb9de0182a";
+    sha256 = "54da7e92468955c4fceacd0c86bd0ec997b0e1ee80d97f67c35a78b719dccab1";
   };
 
   propagatedBuildInputs = lib.optionals isPy27 [ futures backports_functools_lru_cache ];