diff --git a/pkgs/data/themes/material-kwin-decoration/default.nix b/pkgs/data/themes/material-kwin-decoration/default.nix
index 463f86111ee9..9cfe5e76d02e 100644
--- a/pkgs/data/themes/material-kwin-decoration/default.nix
+++ b/pkgs/data/themes/material-kwin-decoration/default.nix
@@ -26,6 +26,12 @@ mkDerivation rec {
     sha256 = "sha256-n+yUmBUrkS+06qLnzl2P6CTQZZbDtJLy+2mDPCcQz9M=";
   };
 
+  # Remove -Werror since it uses deprecated methods
+  postPatch = ''
+    substituteInPlace ./CMakeLists.txt \
+      --replace "add_definitions (-Wall -Werror)" "add_definitions (-Wall)"
+  '';
+
   nativeBuildInputs = [ cmake extra-cmake-modules ];
 
   buildInputs = [