diff --git a/pkgs/build-support/rust/build-rust-package/default.nix b/pkgs/build-support/rust/build-rust-package/default.nix
index b98fb69b40d9d..5d8d0ecc69356 100644
--- a/pkgs/build-support/rust/build-rust-package/default.nix
+++ b/pkgs/build-support/rust/build-rust-package/default.nix
@@ -4,7 +4,6 @@
   fetchCargoTarball,
   fetchCargoVendor,
   stdenv,
-  callPackage,
   cargoBuildHook,
   cargoCheckHook,
   cargoInstallHook,
@@ -24,7 +23,6 @@ lib.extendMkDerivation {
   excludeDrvArgNames = [
     "depsExtraArgs"
     "cargoUpdateHook"
-    "cargoDeps"
     "cargoLock"
   ];
 
@@ -74,9 +72,11 @@ lib.extendMkDerivation {
       ...
     }@args:
 
-    let
-
-      cargoDeps' =
+    lib.optionalAttrs (stdenv.hostPlatform.isDarwin && buildType == "debug") {
+      RUSTFLAGS = "-C split-debuginfo=packed " + (args.RUSTFLAGS or "");
+    }
+    // {
+      cargoDeps =
         if cargoVendorDir != null then
           null
         else if cargoDeps != null then
@@ -127,15 +127,6 @@ lib.extendMkDerivation {
             }
             // depsExtraArgs
           );
-
-      target = stdenv.hostPlatform.rust.rustcTargetSpec;
-      targetIsJSON = lib.hasSuffix ".json" target;
-    in
-    lib.optionalAttrs (stdenv.hostPlatform.isDarwin && buildType == "debug") {
-      RUSTFLAGS = "-C split-debuginfo=packed " + (args.RUSTFLAGS or "");
-    }
-    // {
-      cargoDeps = cargoDeps';
       inherit buildAndTestSubdir;
 
       cargoBuildType = buildType;