diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index 52fc2c8a090..e82e949a249 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -23813,12 +23813,12 @@ in modules // {
   };
 
   traitlets = buildPythonPackage rec {
-    version = "4.2.1";
+    version = "4.2.2";
     name = "traitlets-${version}";
 
     src = pkgs.fetchurl {
       url = "mirror://pypi/t/traitlets/${name}.tar.gz";
-      sha256 = "1h0aryjiqz2f3ykcjb34k5wz6bmzyp5cll7r4k08yfvji4ya7svn";
+      sha256 = "7d7e3070484b2fe490fa55e0acf7023afc5ed9ddabec57405f25c355158e152a";
     };
 
     buildInputs = with self; [ nose mock ];