diff --git a/pkgs/development/python-modules/mypy/extensions.nix b/pkgs/development/python-modules/mypy/extensions.nix
index 36407fd684a..f78b5e1bff4 100644
--- a/pkgs/development/python-modules/mypy/extensions.nix
+++ b/pkgs/development/python-modules/mypy/extensions.nix
@@ -2,14 +2,14 @@
 
 buildPythonPackage rec {
   pname = "mypy_extensions";
-  version = "0.4.1";
+  version = "0.4.2";
 
   # Tests not included in pip package.
   doCheck = false;
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "04h8brrbbx151dfa2cvvlnxgmb5wa00mhd2z7nd20s8kyibfkq1p";
+    sha256 = "a161e3b917053de87dbe469987e173e49fb454eca10ef28b48b384538cc11458";
   };
 
   propagatedBuildInputs = if pythonOlder "3.5" then [ typing ] else [ ];