diff --git a/modules/options/prune-lock.nix b/modules/options/prune-lock.nix
index cd92b80..b34735b 100644
--- a/modules/options/prune-lock.nix
+++ b/modules/options/prune-lock.nix
@@ -30,10 +30,15 @@ let
     pkgs:
     pkgs.writeShellApplication {
       name = "prune-lock";
+      runtimeInputs = [ pkgs.diffutils ];
       text = ''
-        nix flake metadata > /dev/null
         ${prune-cmd pkgs} flake.lock pruned.lock
-        mv pruned.lock flake.lock
+        if cmp -s flake.lock pruned.lock; then
+          rm pruned.lock
+        else
+          mv pruned.lock flake.lock
+        fi
+        nix flake metadata > /dev/null
       '';
     };
 
diff --git a/modules/write-flake.nix b/modules/write-flake.nix
index 33dc05d..da09c31 100644
--- a/modules/write-flake.nix
+++ b/modules/write-flake.nix
@@ -110,9 +110,12 @@ let
     pkgs.writeShellApplication {
       name = "write-flake";
       meta.description = "Generate a flake.nix file";
+      runtimeInputs = [ pkgs.diffutils ];
       text = ''
         cd ${config.flake-file.intoPath}
-        cat ${formatted pkgs} > flake.nix
+        if ! cmp -s ${formatted pkgs} flake.nix; then
+          cat ${formatted pkgs} > flake.nix
+        fi
         ${hooks}
       '';
     };