diff --git a/pkgs/development/libraries/gtkmm/4.x.nix b/pkgs/development/libraries/gtkmm/4.x.nix
index 3c8cce02a639..4025bee7d92b 100644
--- a/pkgs/development/libraries/gtkmm/4.x.nix
+++ b/pkgs/development/libraries/gtkmm/4.x.nix
@@ -19,7 +19,7 @@
 
 stdenv.mkDerivation rec {
   pname = "gtkmm";
-  version = "4.19.1";
+  version = "4.20.0";
 
   outputs = [
     "out"
@@ -28,7 +28,7 @@ stdenv.mkDerivation rec {
 
   src = fetchurl {
     url = "mirror://gnome/sources/gtkmm/${lib.versions.majorMinor version}/gtkmm-${version}.tar.xz";
-    hash = "sha256-K0Q9378M8oxL7ORHpbumICjEnfRcyxs/Q4o6PgvKMao=";
+    hash = "sha256-2q2b+bcPkJdfkXgfx6ZWySOpE3QmH1dsiDzTrr1ZyDM=";
   };
 
   nativeBuildInputs = [