diff --git a/pkgs/applications/misc/buku/default.nix b/pkgs/applications/misc/buku/default.nix
index bde8fab81441..9822a187b9e8 100644
--- a/pkgs/applications/misc/buku/default.nix
+++ b/pkgs/applications/misc/buku/default.nix
@@ -1,14 +1,14 @@
 { stdenv, python3, fetchFromGitHub, fetchpatch }:
 
 with python3.pkgs; buildPythonApplication rec {
-  version = "4.1";
+  version = "4.2";
   pname = "buku";
 
   src = fetchFromGitHub {
     owner = "jarun";
     repo = "buku";
     rev = "v${version}";
-    sha256 = "166l1fmpqn4hys4l0ssc4yd590mmav1w62vm9l5ijhjhmlnrzfax";
+    sha256 = "1ipvhd9wa4iq0763b9h4f3xa6x31bssi6m0595w97mdhh9n6bgxg";
   };
 
   checkInputs = [
@@ -18,6 +18,7 @@ with python3.pkgs; buildPythonApplication rec {
     pylint
     flake8
     pyyaml
+    mypy_extensions
   ];
 
   propagatedBuildInputs = [