diff --git a/pkgs/development/compilers/dart/package-source-builders/audiotags/default.nix b/pkgs/development/compilers/dart/package-source-builders/audiotags/default.nix
index e62eeddf0a24..afe240f484aa 100644
--- a/pkgs/development/compilers/dart/package-source-builders/audiotags/default.nix
+++ b/pkgs/development/compilers/dart/package-source-builders/audiotags/default.nix
@@ -12,14 +12,15 @@ let
     inherit version src;
 
     postPatch = ''
-      cp ${cargoLock.lockFile} Cargo.lock
+      cp --no-preserve=mode ${cargoLock.lockFile} Cargo.lock
     '';
 
     sourceRoot = "${src.name}/rust";
 
-    cargoLock =
-      {
-        _1_4_1.lockFile = ./Cargo-1.4.1.lock;
+    cargoLock.lockFile =
+      rec {
+        _1_4_2 = _1_4_1;
+        _1_4_1 = ./Cargo-1.4.1.lock;
       }
       .${"_" + (lib.replaceStrings [ "." ] [ "_" ] version)} or (throw ''
         Unsupported version of pub 'audiotags': '${version}'