diff --git a/modules/restricted-guests/synapse/package.json b/modules/restricted-guests/synapse/package.json
index 05cfd61802..397948309c 100644
--- a/modules/restricted-guests/synapse/package.json
+++ b/modules/restricted-guests/synapse/package.json
@@ -13,10 +13,10 @@
         "tsc": "echo \"Nothing to tsc\"",
         "lint": "echo \"Nothing to lint\"",
         "lint:ts": "echo \"Nothing to lint:ts\"",
-        "types:py": "node ./scripts/run_in_venv.js tox -e check_types",
-        "lint:py": "node ./scripts/run_in_venv.js tox -e check_codestyle",
-        "lint:fix": "node ./scripts/run_in_venv.js tox -e fix_codestyle",
-        "test": "node ./scripts/run_in_venv.js tox -e py",
+        "types:py": "./scripts/run_in_venv.sh tox -e check_types",
+        "lint:py": "./scripts/run_in_venv.sh tox -e check_codestyle",
+        "lint:fix": "./scripts/run_in_venv.sh tox -e fix_codestyle",
+        "test": "./scripts/run_in_venv.sh tox -e py",
         "depcheck": "echo \"Nothing to check\"",
         "package": "yarn docker:build"
     }
diff --git a/modules/restricted-guests/synapse/scripts/run_in_venv.js b/modules/restricted-guests/synapse/scripts/run_in_venv.js
deleted file mode 100644
index 472d471c32..0000000000
--- a/modules/restricted-guests/synapse/scripts/run_in_venv.js
+++ /dev/null
@@ -1,59 +0,0 @@
-/*
- * Copyright 2023 Nordeck IT + Consulting GmbH
- * Copyright 2025 New Vector Ltd.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-// A script to run a command in a python virtual environment that is stored in
-// `<repo-root>/.venv`. If the virtual environment doesn't exist yet, it will
-// be created.
-//
-// Example: $ node ./run_in_venv.js python --version
-
-const fs = require("fs");
-const path = require("path");
-const child_process = require("child_process");
-
-const cwd = path.resolve(__dirname, "..");
-const venvPath = path.resolve(__dirname, "../../../.venv");
-const venvRelativeToCwd = path.relative(cwd, venvPath);
-
-function run(command) {
-    return new Promise((resolve) => {
-        const proc = child_process.spawn(`source ${venvRelativeToCwd}/bin/activate && ${command}`, [], {
-            cwd,
-            stdio: "inherit",
-            shell: true,
-        });
-
-        proc.on("close", (code) => {
-            console.log("command terminated:", code);
-            resolve();
-        });
-    });
-}
-
-async function main() {
-    if (!fs.existsSync(venvPath) || !fs.lstatSync(venvPath).isDirectory()) {
-        child_process.execSync(`python3 -m venv ${venvRelativeToCwd}`, { cwd });
-        await run("pip install tox");
-        await run('pip install -e ."[dev]"');
-    }
-
-    const command = process.argv.slice(2).join(" ");
-
-    await run(command);
-}
-
-main();
diff --git a/modules/restricted-guests/synapse/scripts/run_in_venv.sh b/modules/restricted-guests/synapse/scripts/run_in_venv.sh
new file mode 100755
index 0000000000..fb20a0a6d4
--- /dev/null
+++ b/modules/restricted-guests/synapse/scripts/run_in_venv.sh
@@ -0,0 +1,36 @@
+#!/usr/bin/env sh
+
+# Copyright 2023 Nordeck IT + Consulting GmbH
+# Copyright 2025 New Vector Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# A script to run a command in a python virtual environment that is stored in
+# `<repo-root>/.venv`. If the virtual environment doesn't exist yet, it will
+# be created.
+#
+# Example: $ ./run_in_venv.sh python --version
+
+set -e
+
+cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.."
+
+repo_root=$(git rev-parse --show-cdup)
+venv_path=${repo_root:-./}.venv
+
+[ -d "$venv_path" ] || python3.11 -m venv "$venv_path"
+source "$venv_path/bin/activate"
+
+pip install -e ."[dev]"
+
+[ $# -gt 1 ] && $*