diff --git a/tests/test_register.py b/tests/test_register.py
index bd925bd5..791be27f 100644
--- a/tests/test_register.py
+++ b/tests/test_register.py
@@ -79,7 +79,8 @@ def test_non_existent_package(register_settings):
         register.register(register_settings, package)
 
 
-def test_values_from_env(monkeypatch):
+@pytest.mark.parametrize("repo", ["pypi", "testpypi"])
+def test_values_from_env_pypi(monkeypatch, repo):
     """Use env vars for settings when run from command line."""
 
     def none_register(*args, **settings_kwargs):
@@ -88,6 +89,8 @@ def none_register(*args, **settings_kwargs):
     replaced_register = pretend.call_recorder(none_register)
     monkeypatch.setattr(register, "register", replaced_register)
     testenv = {
+        "TWINE_REPOSITORY": repo,
+        # Ignored because the TWINE_REPOSITORY is PyPI/TestPyPI
         "TWINE_USERNAME": "this-is-ignored",
         "TWINE_PASSWORD": "pypipassword",
         "TWINE_CERT": "/foo/bar.crt",
@@ -98,3 +101,38 @@ def none_register(*args, **settings_kwargs):
     assert "pypipassword" == register_settings.password
     assert "__token__" == register_settings.username
     assert "/foo/bar.crt" == register_settings.cacert
+
+
+def test_values_from_env_not_pypi(monkeypatch, write_config_file):
+    """Use env vars for settings when run from command line."""
+
+    write_config_file(
+        """
+        [distutils]
+        index-servers =
+            notpypi
+
+        [notpypi]
+        repository: https://upload.example.org/legacy/
+        username:someusername
+        password:password
+        """
+    )
+
+    def none_register(*args, **settings_kwargs):
+        pass
+
+    replaced_register = pretend.call_recorder(none_register)
+    monkeypatch.setattr(register, "register", replaced_register)
+    testenv = {
+        "TWINE_REPOSITORY": "notpypi",
+        "TWINE_USERNAME": "someusername",
+        "TWINE_PASSWORD": "pypipassword",
+        "TWINE_CERT": "/foo/bar.crt",
+    }
+    with helpers.set_env(**testenv):
+        cli.dispatch(["register", helpers.WHEEL_FIXTURE])
+    register_settings = replaced_register.calls[0].args[0]
+    assert "pypipassword" == register_settings.password
+    assert "someusername" == register_settings.username
+    assert "/foo/bar.crt" == register_settings.cacert
diff --git a/tests/test_settings.py b/tests/test_settings.py
index fc64474b..52eb92e9 100644
--- a/tests/test_settings.py
+++ b/tests/test_settings.py
@@ -27,8 +27,11 @@ def test_settings_takes_no_positional_arguments():
         settings.Settings("a", "b", "c")
 
 
-def test_settings_transforms_repository_config(write_config_file):
-    """Set repository config and defaults when .pypirc is provided."""
+def test_settings_transforms_repository_config_pypi(write_config_file):
+    """Set repository config and defaults when .pypirc is provided.
+
+    Ignores the username setting due to PyPI being the index.
+    """
     config_file = write_config_file(
         """
         [pypi]
@@ -50,6 +53,33 @@ def test_settings_transforms_repository_config(write_config_file):
     assert s.disable_progress_bar is False
 
 
+def test_settings_transforms_repository_config_non_pypi(write_config_file):
+    """Set repository config and defaults when .pypirc is provided."""
+    config_file = write_config_file(
+        """
+        [distutils]
+        index-servers =
+            notpypi
+
+        [notpypi]
+        repository: https://upload.example.org/legacy/
+        username:someusername
+        password:password
+        """
+    )
+
+    s = settings.Settings(config_file=config_file, repository_name="notpypi")
+    assert s.repository_config["repository"] == "https://upload.example.org/legacy/"
+    assert s.sign is False
+    assert s.sign_with == "gpg"
+    assert s.identity is None
+    assert s.username == "someusername"
+    assert s.password == "password"
+    assert s.cacert is None
+    assert s.client_cert is None
+    assert s.disable_progress_bar is False
+
+
 @pytest.mark.parametrize(
     "verbose, log_level", [(True, logging.INFO), (False, logging.WARNING)]
 )