diff --git a/pkgs/by-name/ma/matrix-appservice-slack/package.json b/pkgs/by-name/ma/matrix-appservice-slack/package.json
deleted file mode 100644
index d4a27436aea1ea..00000000000000
--- a/pkgs/by-name/ma/matrix-appservice-slack/package.json
+++ /dev/null
@@ -1,96 +0,0 @@
-{
-  "name": "matrix-appservice-slack",
-  "version": "2.1.2",
-  "description": "A Matrix <--> Slack bridge",
-  "engines": {
-    "node": ">=16 <=18"
-  },
-  "main": "app.js",
-  "scripts": {
-    "prepare": "yarn build",
-    "start": "node ./lib/app.js",
-    "build": "yarn build:app && yarn build:widget",
-    "build:app": "tsc --build",
-    "build:widget": "vite build --config widget/vite.config.ts",
-    "test": "yarn test:unit && yarn test:integration",
-    "test:unit": "mocha --require ts-node/register --recursive tests/unit/*.ts",
-    "test:integration": "mocha --exit --reporter list --ui bdd --require ts-node/register --recursive tests/integration/*.ts",
-    "test:postgres": "SLACKBRIDGE_TEST_ENABLEPG=yes mocha --reporter list --ui bdd --require ts-node/register --recursive tests/integration/PgDatastoreTest.ts",
-    "lint": "eslint -c .eslintrc.js ./src && eslint -c ./widget/.eslintrc.js 'widget/src/**/*.{ts,tsx}'"
-  },
-  "repository": {
-    "type": "git",
-    "url": "git+https://github.com/matrix-org/matrix-appservice-slack.git"
-  },
-  "keywords": [
-    "matrix-org",
-    "slack"
-  ],
-  "author": "Matrix.org",
-  "license": "Apache-2.0",
-  "bugs": {
-    "url": "https://github.com/matrix-org/matrix-appservice-slack/issues"
-  },
-  "homepage": "https://github.com/matrix-org/matrix-appservice-slack#readme",
-  "dependencies": {
-    "@alloc/quick-lru": "^5.2.0",
-    "@slack/logger": "^3.0.0",
-    "@slack/rtm-api": "^6.0.0",
-    "@slack/web-api": "^6.7.2",
-    "Slackdown": "git+https://Half-Shot@github.com/half-shot/slackdown.git",
-    "ajv": "^8.12.0",
-    "axios": "^0.27.2",
-    "classnames": "^2.3.2",
-    "escape-string-regexp": "^4.0.0",
-    "https-proxy-agent": "^5.0.1",
-    "matrix-appservice-bridge": "^8.1.2",
-    "matrix-widget-api": "^1.1.1",
-    "minimist": "^1.2.6",
-    "nedb": "^1.8.0",
-    "node-emoji": "^1.10.0",
-    "nunjucks": "^3.2.4",
-    "p-queue": "^6.0.0",
-    "pg-promise": "^10.11.1",
-    "randomstring": "^1.2.1",
-    "react": "^18.2.0",
-    "react-dom": "^18.2.0",
-    "url-join": "^5.0.0",
-    "uuid": "^8.3.2",
-    "yargs": "17.5.1"
-  },
-  "devDependencies": {
-    "@tailwindcss/forms": "^0.5.3",
-    "@tsconfig/node16": "^1.0.3",
-    "@types/chai": "^4.2.21",
-    "@types/js-yaml": "^4.0.2",
-    "@types/mocha": "^9.1.1",
-    "@types/nedb": "^1.8.12",
-    "@types/node": "^18.6.1",
-    "@types/node-emoji": "^1.8.1",
-    "@types/nunjucks": "^3.1.5",
-    "@types/randomstring": "^1.1.7",
-    "@types/react": "^18.0.27",
-    "@types/react-dom": "^18.0.10",
-    "@types/uuid": "^8.3.1",
-    "@types/yargs": "17.0.10",
-    "@typescript-eslint/eslint-plugin": "^5.0.0",
-    "@typescript-eslint/parser": "^5.50.0",
-    "@vitejs/plugin-react": "^3.1.0",
-    "autoprefixer": "^10.4.13",
-    "chai": "^4.3.4",
-    "eslint": "^8.20.0",
-    "eslint-plugin-jsdoc": "^39.3.3",
-    "eslint-plugin-prefer-arrow": "^1.2.3",
-    "eslint-plugin-react": "^7.32.2",
-    "eslint-plugin-react-hooks": "^4.6.0",
-    "js-yaml": "^4.1.0",
-    "mocha": "^10.0.0",
-    "postcss": "^8.4.21",
-    "prom-client": "^14.0.1",
-    "source-map-support": "^0.5.19",
-    "tailwindcss": "^3.2.4",
-    "ts-node": "^10.1.0",
-    "typescript": "^4.4.3",
-    "vite": "^4.1.1"
-  }
-}
diff --git a/pkgs/by-name/ma/matrix-appservice-slack/package.nix b/pkgs/by-name/ma/matrix-appservice-slack/package.nix
index b37ebccbf2f275..480bd57ba3c8bb 100644
--- a/pkgs/by-name/ma/matrix-appservice-slack/package.nix
+++ b/pkgs/by-name/ma/matrix-appservice-slack/package.nix
@@ -1,55 +1,74 @@
 {
   lib,
+  stdenv,
   fetchFromGitHub,
   fetchYarnDeps,
+  yarnConfigHook,
+  yarnBuildHook,
+  nodejs_20,
   makeWrapper,
-  mkYarnPackage,
-  nodejs_18,
   callPackage,
 }:
 
 let
-  data = lib.importJSON ./pin.json;
-  nodejs = nodejs_18;
+  nodejs = nodejs_20;
   matrix-sdk-crypto-nodejs = callPackage ./matrix-sdk-crypto-nodejs-0_1_0-beta_3/package.nix { };
 in
-mkYarnPackage rec {
-  inherit nodejs;
-
+stdenv.mkDerivation rec {
   pname = "matrix-appservice-slack";
-  version = data.version;
+  version = "2.1.2";
 
-  packageJSON = ./package.json;
   src = fetchFromGitHub {
     owner = "matrix-org";
     repo = "matrix-appservice-slack";
-    rev = data.version;
-    hash = data.srcHash;
+    rev = version;
+    hash = "sha256-e9k+5xvgHkVt/fKAr0XhYjbEzHYwdGRdqiPWWbT0T5M=";
   };
 
-  offlineCache = fetchYarnDeps {
+  nativeBuildInputs = [
+    makeWrapper
+    nodejs
+    yarnConfigHook
+    yarnBuildHook
+  ];
+
+  postPatch = ''
+    # upstream locks the supported node version range down, which we don't want
+    substituteInPlace package.json \
+      --replace-fail '"node": ">=16 <=18"' '"node": ">=16"'
+  '';
+
+  yarnOfflineCache = fetchYarnDeps {
     yarnLock = src + "/yarn.lock";
-    sha256 = data.yarnHash;
-  };
-  packageResolutions = {
-    "@matrix-org/matrix-sdk-crypto-nodejs" =
-      "${matrix-sdk-crypto-nodejs}/lib/node_modules/@matrix-org/matrix-sdk-crypto-nodejs";
+    hash = "sha256-fw4gXh4wfzHFgUYiEAvbhVrjno/E70iMhdk60F3Oxgg=";
   };
 
-  nativeBuildInputs = [ makeWrapper ];
+  preBuild = ''
+    # matrix-sdk-crypto-nodejs needs rust to be built from source, which we can achieve in a separate derivation
 
-  buildPhase = ''
-    runHook preBuild
-    yarn run build
-    runHook postBuild
+    # first, we ensure the separately built module's version is actually the same as the version in the lockfile
+    diff ${matrix-sdk-crypto-nodejs}/lib/node_modules/@matrix-org/matrix-sdk-crypto-nodejs/package.json node_modules/@matrix-org/matrix-sdk-crypto-nodejs/package.json
+
+    # then we copy it into node_modules
+    rm -r node_modules/@matrix-org/matrix-sdk-crypto-nodejs
+    ln -s ${matrix-sdk-crypto-nodejs}/lib/node_modules/@matrix-org/matrix-sdk-crypto-nodejs node_modules/@matrix-org/matrix-sdk-crypto-nodejs
   '';
 
-  postInstall = ''
-    makeWrapper '${nodejs}/bin/node' "$out/bin/matrix-appservice-slack" --add-flags \
-        "$out/libexec/matrix-appservice-slack/deps/matrix-appservice-slack/lib/app.js"
+  installPhase = ''
+    runHook preInstall
+
+    mkdir -p "$out"/libexec/matrix-appservice-slack
+    cp -r package.json lib node_modules "$out"/libexec/matrix-appservice-slack
+
+    makeWrapper '${lib.getExe nodejs}' "$out/bin/matrix-appservice-slack" --add-flags \
+        "$out/libexec/matrix-appservice-slack/lib/app.js"
+
+    runHook postInstall
   '';
 
-  doDist = false;
+  passthru = {
+    inherit matrix-sdk-crypto-nodejs;
+  };
 
   meta = with lib; {
     description = "Matrix <--> Slack bridge";
diff --git a/pkgs/by-name/ma/matrix-appservice-slack/pin.json b/pkgs/by-name/ma/matrix-appservice-slack/pin.json
deleted file mode 100644
index 3adfcbabae62b4..00000000000000
--- a/pkgs/by-name/ma/matrix-appservice-slack/pin.json
+++ /dev/null
@@ -1,5 +0,0 @@
-{
-  "version": "2.1.2",
-  "srcHash": "sha256-e9k+5xvgHkVt/fKAr0XhYjbEzHYwdGRdqiPWWbT0T5M=",
-  "yarnHash": "0266rrfx0fnrhn64ivy4iygf6nl5vc5i08j6h72k2zrh3rg203kz"
-}
diff --git a/pkgs/by-name/ma/matrix-appservice-slack/update.sh b/pkgs/by-name/ma/matrix-appservice-slack/update.sh
deleted file mode 100755
index dc3bab3311f21c..00000000000000
--- a/pkgs/by-name/ma/matrix-appservice-slack/update.sh
+++ /dev/null
@@ -1,36 +0,0 @@
-#!/usr/bin/env nix-shell
-#!nix-shell -I nixpkgs=../../../../ -i bash -p nix curl jq prefetch-yarn-deps nix-prefetch-github nix-prefetch-git
-
-if [ "$#" -gt 1 ] || [[ "$1" == -* ]]; then
-  echo "Regenerates packaging data for matrix-appservice-slack."
-  echo "Usage: $0 [git release tag]"
-  exit 1
-fi
-
-version="$1"
-
-set -euo pipefail
-
-if [ -z "$version" ]; then
-  version="$(curl "https://api.github.com/repos/matrix-org/matrix-appservice-slack/releases?per_page=1" | jq -r '.[0].tag_name')"
-fi
-
-src="https://raw.githubusercontent.com/matrix-org/matrix-appservice-slack/$version"
-src_hash=$(nix-prefetch-github matrix-org matrix-appservice-slack --rev ${version} | jq -r .hash)
-
-tmpdir=$(mktemp -d)
-trap 'rm -rf "$tmpdir"' EXIT
-
-pushd $tmpdir
-curl -O "$src/yarn.lock"
-yarn_hash=$(prefetch-yarn-deps yarn.lock)
-popd
-
-curl -O "$src/package.json"
-cat > pin.json << EOF
-{
-  "version": "$version",
-  "srcHash": "$src_hash",
-  "yarnHash": "$yarn_hash"
-}
-EOF