diff --git a/pkgs/servers/mastodon/default.nix b/pkgs/servers/mastodon/default.nix
index d75e148bf1e3..31a092359cfc 100644
--- a/pkgs/servers/mastodon/default.nix
+++ b/pkgs/servers/mastodon/default.nix
@@ -1,29 +1,27 @@
-{ lib, stdenv, nodejs-slim, mkYarnPackage, fetchFromGitHub, bundlerEnv, nixosTests
+{ lib, stdenv, nodejs-slim, bundlerEnv, nixosTests
 , yarn, callPackage, imagemagick, ffmpeg, file, ruby_3_0, writeShellScript
 , fetchYarnDeps, fixup_yarn_lock
 , brotli
 
   # Allow building a fork or custom version of Mastodon:
 , pname ? "mastodon"
-, version ? import ./version.nix
-, srcOverride ? null
-, dependenciesDir ? ./.  # Expected to contain gemset.nix
-, yarnHash ? import ./yarn-hash.nix
+, version ? srcOverride.version
+  # src is a package
+, srcOverride ? callPackage ./source.nix {}
+, gemset ? ./. + "/gemset.nix"
+, yarnHash ? srcOverride.yarnHash
 }:
 
 stdenv.mkDerivation rec {
   inherit pname version;
 
-  # Using overrideAttrs on src does not build the gems and modules with the overridden src.
-  # Putting the callPackage up in the arguments list also does not work.
-  src = if srcOverride != null then srcOverride else callPackage ./source.nix {};
+  src = srcOverride;
 
   mastodonGems = bundlerEnv {
     name = "${pname}-gems-${version}";
-    inherit version;
+    inherit version gemset;
     ruby = ruby_3_0;
     gemdir = src;
-    gemset = dependenciesDir + "/gemset.nix";
     # This fix (copied from https://github.com/NixOS/nixpkgs/pull/76765) replaces the gem
     # symlinks with directories, resolving this error when running rake:
     #   /nix/store/451rhxkggw53h7253izpbq55nrhs7iv0-mastodon-gems-3.0.1/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/lib/bundler/settings.rb:6:in `<module:Bundler>': uninitialized constant Bundler::Settings (NameError)
diff --git a/pkgs/servers/mastodon/source.nix b/pkgs/servers/mastodon/source.nix
index db090f192740..995b58476d78 100644
--- a/pkgs/servers/mastodon/source.nix
+++ b/pkgs/servers/mastodon/source.nix
@@ -1,12 +1,16 @@
 # This file was generated by pkgs.mastodon.updateScript.
-{ fetchFromGitHub, applyPatches }: let
+{ fetchFromGitHub, applyPatches }:
+let
+  version = "4.1.9";
+in
+applyPatches {
+  inherit version;
   src = fetchFromGitHub {
     owner = "mastodon";
     repo = "mastodon";
-    rev = "v4.1.9";
+    rev = "${version}";
     hash = "sha256-xpE/mg2AeioW6NThUjLS+SBxGavG4w1xtp3BOMADfYo=";
   };
-in applyPatches {
-  inherit src;
   patches = [];
+  yarnHash = "sha256-e3rl/WuKXaUdeDEYvo1sSubuIwtBjkbguCYdAijwXOA=";
 }
diff --git a/pkgs/servers/mastodon/update.sh b/pkgs/servers/mastodon/update.sh
index 78a67e95cad9..6955f9e61805 100755
--- a/pkgs/servers/mastodon/update.sh
+++ b/pkgs/servers/mastodon/update.sh
@@ -56,7 +56,7 @@ if [[ -z "$REVISION" ]]; then
     VERSION="$(echo "$REVISION" | cut -c2-)"
 fi
 
-rm -f gemset.nix version.nix source.nix
+rm -f gemset.nix source.nix
 cd "$(dirname "${BASH_SOURCE[0]}")" || exit 1
 
 WORK_DIR=$(mktemp -d)
@@ -77,23 +77,24 @@ trap cleanup EXIT
 
 echo "Fetching source code $REVISION"
 JSON=$(nix-prefetch-github "$OWNER" "$REPO" --rev "$REVISION" 2> $WORK_DIR/nix-prefetch-git.out)
-HASH="$(echo "$JSON" | jq -r .hash)"
-
-echo "Creating version.nix"
-echo "\"$VERSION\"" | sed 's/^"v/"/' > version.nix
+HASH=$(echo "$JSON" | jq -r .hash)
 
 cat > source.nix << EOF
 # This file was generated by pkgs.mastodon.updateScript.
-{ fetchFromGitHub, applyPatches }: let
+{ fetchFromGitHub, applyPatches }:
+let
+  version = "$VERSION";
+in
+applyPatches {
+  inherit version;
   src = fetchFromGitHub {
     owner = "$OWNER";
     repo = "$REPO";
-    rev = "$REVISION";
+    rev = "\${version}";
     hash = "$HASH";
   };
-in applyPatches {
-  inherit src;
   patches = [$PATCHES];
+  yarnHash = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
 }
 EOF
 SOURCE_DIR="$(nix-build --no-out-link -E '(import <nixpkgs> {}).callPackage ./source.nix {}')"
@@ -105,4 +106,4 @@ echo "" >> gemset.nix  # Create trailing newline to please EditorConfig checks
 echo "Creating yarn-hash.nix"
 YARN_HASH="$(prefetch-yarn-deps "$SOURCE_DIR/yarn.lock")"
 YARN_HASH="$(nix hash to-sri --type sha256 "$YARN_HASH")"
-printf '"%s"\n' "$YARN_HASH" > yarn-hash.nix
+sed -i "s/sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=/$YARN_HASH/g" source.nix
diff --git a/pkgs/servers/mastodon/version.nix b/pkgs/servers/mastodon/version.nix
deleted file mode 100644
index 2647b9c70ad8..000000000000
--- a/pkgs/servers/mastodon/version.nix
+++ /dev/null
@@ -1 +0,0 @@
-"4.1.9"
diff --git a/pkgs/servers/mastodon/yarn-hash.nix b/pkgs/servers/mastodon/yarn-hash.nix
deleted file mode 100644
index f0e3e8a27af7..000000000000
--- a/pkgs/servers/mastodon/yarn-hash.nix
+++ /dev/null
@@ -1 +0,0 @@
-"sha256-e3rl/WuKXaUdeDEYvo1sSubuIwtBjkbguCYdAijwXOA="