diff --git a/modules/gnome-fractional-scaling.home.nix b/modules/gnome-fractional-scaling.home.nix
index 3d3d35f..d6c1cc8 100644
--- a/modules/gnome-fractional-scaling.home.nix
+++ b/modules/gnome-fractional-scaling.home.nix
@@ -10,6 +10,7 @@
 
   # Overlays.
   # https://nixos.wiki/wiki/Overlays#In_NixOS
+  # https://discourse.nixos.org/t/use-specific-pkg-version-in-overlay/32741/3
   nixpkgs.overlays = [
     (
       # Patched version of mutter 44.2.
@@ -32,15 +33,19 @@
       final: prev: {
         # Elements of pkgs.gnome must be taken from gfinal and gprev.
         gnome = prev.gnome.overrideScope' (gfinal: gprev: {
-          mutter = gprev.mutter.overrideAttrs (oldAttrs: {
-            patches = (oldAttrs.patches or []) ++ [
-              (prev.fetchpatch {
-                url = "https://salsa.debian.org/gnome-team/mutter/-/raw/ubuntu/44.2-3ubuntu1/debian/patches/ubuntu/x11-Add-support-for-fractional-scaling-using-Randr.patch";
-                # Determining the hash: https://github.com/NixOS/nixpkgs/issues/191128#issuecomment-1246030431
-                hash = "sha256-GCtz87C1NgxenYE5nbxcIIxqNhutmdngscnlK10fRyQ=";
-              })
-            ];
-          });
+          mutter = gprev.mutter.overrideAttrs (oldAttrs:
+            if oldAttrs.version == "44.2" then
+              {
+                patches = (oldAttrs.patches or []) ++ [
+                  (prev.fetchpatch {
+                    url = "https://salsa.debian.org/gnome-team/mutter/-/raw/ubuntu/44.2-3ubuntu1/debian/patches/ubuntu/x11-Add-support-for-fractional-scaling-using-Randr.patch";
+                    # Determining the hash: https://github.com/NixOS/nixpkgs/issues/191128#issuecomment-1246030431
+                    hash = "sha256-GCtz87C1NgxenYE5nbxcIIxqNhutmdngscnlK10fRyQ=";
+                  })
+                ];
+              }
+            else throw "Mutter version mismatch. Please update patch."
+          );
         });
       }
     )