diff --git a/.github/workflows/tests-nix-macos.yml b/.github/workflows/tests-nix-macos.yml
index d4309390..02b139b7 100644
--- a/.github/workflows/tests-nix-macos.yml
+++ b/.github/workflows/tests-nix-macos.yml
@@ -7,7 +7,7 @@ jobs:
     strategy:
       matrix:
         platform:
-          - macos-12
+          - macos-13
     runs-on: ${{ matrix.platform }}
     steps:
     - uses: actions/checkout@v4
diff --git a/sample_projects/bin_with_git_submodule_dep/Cargo.nix b/sample_projects/bin_with_git_submodule_dep/Cargo.nix
index e731beef..ecfd54dd 100644
--- a/sample_projects/bin_with_git_submodule_dep/Cargo.nix
+++ b/sample_projects/bin_with_git_submodule_dep/Cargo.nix
@@ -5,6 +5,7 @@
 
 { nixpkgs ? <nixpkgs>
 , pkgs ? import nixpkgs { config = {}; }
+, fetchurl ? pkgs.fetchurl
 , lib ? pkgs.lib
 , stdenv ? pkgs.stdenv
 , buildRustCrateForPkgs ? pkgs: pkgs.buildRustCrate
@@ -61,6 +62,8 @@ rec {
     };
   };
 
+
+
   # A derivation that joins the outputs of all workspace members together.
   allWorkspaceMembers = pkgs.symlinkJoin {
       name = "all-workspace-members";
@@ -1386,6 +1389,26 @@ rec {
     debug_assertions = false;
   };
 
+  registryUrl = { registries, url, crate, version, sha256 }:
+    let dl = registries.${url}.dl;
+        tmpl = [ "{crate}" "{version}" "{prefix}" "{lowerprefix}" "{sha256-checksum}" ];
+    in
+      with lib.strings;
+    if lib.lists.any (i: hasInfix "{}" dl) tmpl then
+      let prefix =
+            if builtins.stringLength crate == 1 then
+              "1"
+            else if builtins.stringLength crate == 2 then
+              "2"
+            else
+              "${builtins.substring 0 2 crate}/${builtins.substring 2 (builtins.stringLength crate - 2) crate}";
+      in
+        builtins.replaceStrings tmpl [
+          crate version prefix (lib.strings.toLower prefix) sha256
+        ]
+    else
+      "${dl}/${crate}/${version}/download";
+
   /* Filters common temp files and build files. */
   # TODO(pkolloch): Substitute with gitignore filter
   sourceFilter = name: type:
diff --git a/sample_projects/codegen/Cargo.nix b/sample_projects/codegen/Cargo.nix
index 8ff30078..18031924 100644
--- a/sample_projects/codegen/Cargo.nix
+++ b/sample_projects/codegen/Cargo.nix
@@ -5,6 +5,7 @@
 
 { nixpkgs ? <nixpkgs>
 , pkgs ? import nixpkgs { config = {}; }
+, fetchurl ? pkgs.fetchurl
 , lib ? pkgs.lib
 , stdenv ? pkgs.stdenv
 , buildRustCrateForPkgs ? pkgs: pkgs.buildRustCrate
@@ -61,6 +62,8 @@ rec {
     };
   };
 
+
+
   # A derivation that joins the outputs of all workspace members together.
   allWorkspaceMembers = pkgs.symlinkJoin {
       name = "all-workspace-members";
@@ -561,6 +564,26 @@ rec {
     debug_assertions = false;
   };
 
+  registryUrl = { registries, url, crate, version, sha256 }:
+    let dl = registries.${url}.dl;
+        tmpl = [ "{crate}" "{version}" "{prefix}" "{lowerprefix}" "{sha256-checksum}" ];
+    in
+      with lib.strings;
+    if lib.lists.any (i: hasInfix "{}" dl) tmpl then
+      let prefix =
+            if builtins.stringLength crate == 1 then
+              "1"
+            else if builtins.stringLength crate == 2 then
+              "2"
+            else
+              "${builtins.substring 0 2 crate}/${builtins.substring 2 (builtins.stringLength crate - 2) crate}";
+      in
+        builtins.replaceStrings tmpl [
+          crate version prefix (lib.strings.toLower prefix) sha256
+        ]
+    else
+      "${dl}/${crate}/${version}/download";
+
   /* Filters common temp files and build files. */
   # TODO(pkolloch): Substitute with gitignore filter
   sourceFilter = name: type:
diff --git a/sample_projects/sub_dir_crates/Cargo.nix b/sample_projects/sub_dir_crates/Cargo.nix
index 6f2bdd02..f0f20888 100644
--- a/sample_projects/sub_dir_crates/Cargo.nix
+++ b/sample_projects/sub_dir_crates/Cargo.nix
@@ -5,6 +5,7 @@
 
 { nixpkgs ? <nixpkgs>
 , pkgs ? import nixpkgs { config = {}; }
+, fetchurl ? pkgs.fetchurl
 , lib ? pkgs.lib
 , stdenv ? pkgs.stdenv
 , buildRustCrateForPkgs ? pkgs: pkgs.buildRustCrate
@@ -61,6 +62,8 @@ rec {
     };
   };
 
+
+
   # A derivation that joins the outputs of all workspace members together.
   allWorkspaceMembers = pkgs.symlinkJoin {
       name = "all-workspace-members";
@@ -170,6 +173,26 @@ rec {
     debug_assertions = false;
   };
 
+  registryUrl = { registries, url, crate, version, sha256 }:
+    let dl = registries.${url}.dl;
+        tmpl = [ "{crate}" "{version}" "{prefix}" "{lowerprefix}" "{sha256-checksum}" ];
+    in
+      with lib.strings;
+    if lib.lists.any (i: hasInfix "{}" dl) tmpl then
+      let prefix =
+            if builtins.stringLength crate == 1 then
+              "1"
+            else if builtins.stringLength crate == 2 then
+              "2"
+            else
+              "${builtins.substring 0 2 crate}/${builtins.substring 2 (builtins.stringLength crate - 2) crate}";
+      in
+        builtins.replaceStrings tmpl [
+          crate version prefix (lib.strings.toLower prefix) sha256
+        ]
+    else
+      "${dl}/${crate}/${version}/download";
+
   /* Filters common temp files and build files. */
   # TODO(pkolloch): Substitute with gitignore filter
   sourceFilter = name: type: