diff --git a/pre_commit/languages/ruby.py b/pre_commit/languages/ruby.py
index b4d4b45a..4416f728 100644
--- a/pre_commit/languages/ruby.py
+++ b/pre_commit/languages/ruby.py
@@ -39,7 +39,6 @@ def get_env_patch(
         ('GEM_HOME', os.path.join(venv, 'gems')),
         ('GEM_PATH', UNSET),
         ('BUNDLE_IGNORE_CONFIG', '1'),
-        ('BUNDLE_GEMFILE', os.devnull),
     )
     if language_version == 'system':
         patches += (
diff --git a/tests/languages/ruby_test.py b/tests/languages/ruby_test.py
index b312c7fd..9cfaad5d 100644
--- a/tests/languages/ruby_test.py
+++ b/tests/languages/ruby_test.py
@@ -123,8 +123,9 @@ def test_ruby_hook_language_version(tmp_path):
 def test_ruby_with_bundle_disable_shared_gems(tmp_path):
     workdir = tmp_path.joinpath('workdir')
     workdir.mkdir()
-    # this Gemfile is missing `source`
-    workdir.joinpath('Gemfile').write_text('gem "lol_hai"\n')
+    # this needs a `source` or there's a deprecation warning
+    # silencing this with `BUNDLE_GEMFILE` breaks some tools (#2739)
+    workdir.joinpath('Gemfile').write_text('source ""\ngem "lol_hai"\n')
     # this bundle config causes things to be written elsewhere
     bundle = workdir.joinpath('.bundle')
     bundle.mkdir()
@@ -134,5 +135,5 @@ def test_ruby_with_bundle_disable_shared_gems(tmp_path):
     )
 
     with cwd(workdir):
-        # `3.2.0` has new enough `gem` requiring `source` and reading `.bundle`
+        # `3.2.0` has new enough `gem` reading `.bundle`
         test_ruby_hook_language_version(tmp_path)