@@ -17,7 +17,6 @@
 from pre_commit.prefix import Prefix
 from pre_commit.util import cmd_output
 from pre_commit.util import cmd_output_b
-from pre_commit.util import rmtree
 
 ENVIRONMENT_DIR = 'node_env'
 run_hook = lang_base.basic_run_hook
@@ -77,7 +76,18 @@ def health_check(prefix: Prefix, version: str) -> str | None:
 def install_environment(
         prefix: Prefix, version: str, additional_dependencies: Sequence[str],
 ) -> None:
-    assert prefix.exists('package.json')
+    if prefix.exists('.git') and prefix.exists('package.json'):
+        # this requires a new-enough npm (2019ish?)
+        pkgs = (f'git+file://{prefix.prefix_dir}', *additional_dependencies)
+    else:
+        pkgs = (*additional_dependencies,)
+
+    if not pkgs:
+        raise AssertionError(
+            '`language: node` must have package.json or '
+            'additional_dependencies',
+        )
+
     envdir = lang_base.environment_dir(prefix, ENVIRONMENT_DIR, version)
 
     # https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx?f=255&MSPPError=-2147217396#maxpath
@@ -89,22 +99,5 @@ def install_environment(
     cmd_output_b(*cmd)
 
     with in_env(prefix, version):
-        # https://npm.community/t/npm-install-g-git-vs-git-clone-cd-npm-install-g/5449
-        # install as if we installed from git
-
-        local_install_cmd = (
-            'npm', 'install', '--include=dev', '--include=prod',
-            '--ignore-prepublish', '--no-progress', '--no-save',
-        )
-        lang_base.setup_cmd(prefix, local_install_cmd)
-
-        _, pkg, _ = cmd_output('npm', 'pack', cwd=prefix.prefix_dir)
-        pkg = prefix.path(pkg.strip())
-
-        install = ('npm', 'install', '-g', pkg, *additional_dependencies)
+        install = ('npm', 'install', '--allow-git=root', '-g', *pkgs)
         lang_base.setup_cmd(prefix, install)
-
-        # clean these up after installation
-        if prefix.exists('node_modules'):  # pragma: win32 no cover
-            rmtree(prefix.path('node_modules'))
-        os.remove(pkg)
@@ -37,8 +37,8 @@ def _get_default_directory() -> str:
 
 
 _LOCAL_RESOURCES = (
-    'Cargo.toml', 'main.go', 'go.mod', 'main.rs', '.npmignore',
-    'package.json', 'pre-commit-package-dev-1.rockspec',
+    'Cargo.toml', 'main.go', 'go.mod', 'main.rs',
+    'pre-commit-package-dev-1.rockspec',
     'pre_commit_placeholder_package.gemspec', 'setup.py',
     'environment.yml', 'Makefile.PL', 'pubspec.yaml',
     'renv.lock', 'renv/activate.R', 'renv/LICENSE.renv',
 
@@ -15,7 +15,9 @@
 from pre_commit.prefix import Prefix
 from pre_commit.store import _make_local_repo
 from pre_commit.util import cmd_output
+from pre_commit.util import cmd_output_b
 from testing.language_helpers import run_language
+from testing.util import git_commit
 from testing.util import xfailif_windows
 
 
@@ -40,6 +42,12 @@ def find_exe_mck():
         yield mck
 
 
+def _make_repo(r):
+    cmd_output_b('git', 'init', r)
+    cmd_output_b('git', 'add', '.', cwd=r)
+    git_commit(cwd=r)
+
+
 @pytest.mark.usefixtures('is_linux')
 def test_sets_system_when_node_and_npm_are_available(find_exe_mck):
     find_exe_mck.return_value = '/path/to/exe'
@@ -61,6 +69,7 @@ def test_sets_default_on_windows(find_exe_mck):
 @xfailif_windows  # pragma: win32 no cover
 def test_healthy_system_node(tmpdir):
     tmpdir.join('package.json').write('{"name": "t", "version": "1.0.0"}')
+    _make_repo(str(tmpdir))
 
     prefix = Prefix(str(tmpdir))
     node.install_environment(prefix, 'system', ())
@@ -75,6 +84,7 @@ def test_unhealthy_if_system_node_goes_missing(tmpdir):
 
     prefix_dir = tmpdir.join('prefix').ensure_dir()
     prefix_dir.join('package.json').write('{"name": "t", "version": "1.0.0"}')
+    _make_repo(str(prefix_dir))
 
     path = ('PATH', (str(bin_dir), os.pathsep, envcontext.Var('PATH')))
     with envcontext.envcontext((path,)):
@@ -101,6 +111,7 @@ def test_installs_without_links_outside_env(tmpdir):
             'dependencies': {'lodash': '*'},
         }),
     )
+    _make_repo(str(tmpdir))
 
     prefix = Prefix(str(tmpdir))
     node.install_environment(prefix, 'system', ())
@@ -124,6 +135,7 @@ def _make_hello_world(tmp_path):
         '#!/usr/bin/env node\n'
         'console.log("Hello World");\n',
     )
+    _make_repo(str(tmp_path))
 
 
 def test_node_hook_system(tmp_path):