diff --git a/changelog.d/1652.change.rst b/changelog.d/1652.change.rst
index 545365ac83..387d212ced 100644
--- a/changelog.d/1652.change.rst
+++ b/changelog.d/1652.change.rst
@@ -1 +1 @@
-Added the ``build_meta:legacy`` backend, a "compatibility mode" PEP 517 backend that can be used as the default when ``build-backend`` is left unspecified in ``pyproject.toml``.
+Added the ``build_meta:__legacy__`` backend, a "compatibility mode" PEP 517 backend that can be used as the default when ``build-backend`` is left unspecified in ``pyproject.toml``.
diff --git a/setuptools/build_meta.py b/setuptools/build_meta.py
index e16f319e3c..70b7ab230e 100644
--- a/setuptools/build_meta.py
+++ b/setuptools/build_meta.py
@@ -40,7 +40,7 @@
            'prepare_metadata_for_build_wheel',
            'build_wheel',
            'build_sdist',
-           'legacy',
+           '__legacy__',
            'SetupRequirementsError']
 
 class SetupRequirementsError(BaseException):
@@ -228,4 +228,4 @@ def run_setup(self, setup_script='setup.py'):
 
 
 # The legacy backend
-legacy = _BuildMetaLegacyBackend()
+__legacy__ = _BuildMetaLegacyBackend()
diff --git a/setuptools/tests/test_build_meta.py b/setuptools/tests/test_build_meta.py
index 42e3098ae1..6236b9f42b 100644
--- a/setuptools/tests/test_build_meta.py
+++ b/setuptools/tests/test_build_meta.py
@@ -270,7 +270,7 @@ def test_build_sdist_relative_path_import(self, tmpdir_cwd):
 
 
 class TestBuildMetaLegacyBackend(TestBuildMetaBackend):
-    backend_name = 'setuptools.build_meta:legacy'
+    backend_name = 'setuptools.build_meta:__legacy__'
 
     # build_meta_legacy-specific tests
     def test_build_sdist_relative_path_import(self, tmpdir_cwd):