diff --git a/zerver/tests/test_auth_backends.py b/zerver/tests/test_auth_backends.py
index fdf77ea8a7..6632ef7006 100644
--- a/zerver/tests/test_auth_backends.py
+++ b/zerver/tests/test_auth_backends.py
@@ -3292,7 +3292,6 @@ class SAMLAuthBackendTest(SocialAuthBase):
 
 
 class AppleAuthMixin:
-    BACKEND_CLASS = AppleAuthBackend
     CLIENT_KEY_SETTING = "SOCIAL_AUTH_APPLE_KEY"
     AUTHORIZATION_URL = "https://appleid.apple.com/auth/authorize"
     ACCESS_TOKEN_URL = "https://appleid.apple.com/auth/token"
@@ -3329,6 +3328,7 @@ class AppleAuthMixin:
 
 
 class AppleIdAuthBackendTest(AppleAuthMixin, SocialAuthBase):
+    BACKEND_CLASS = AppleAuthBackend
     LOGIN_URL = "/accounts/login/social/apple"
     SIGNUP_URL = "/accounts/register/social/apple"
 
@@ -3462,6 +3462,7 @@ class AppleIdAuthBackendTest(AppleAuthMixin, SocialAuthBase):
 
 
 class AppleAuthBackendNativeFlowTest(AppleAuthMixin, SocialAuthBase):
+    BACKEND_CLASS = AppleAuthBackend
     SIGNUP_URL = "/complete/apple/"
     LOGIN_URL = "/complete/apple/"
 
diff --git a/zproject/backends.py b/zproject/backends.py
index b8f7bbb756..76b7d4994f 100644
--- a/zproject/backends.py
+++ b/zproject/backends.py
@@ -1630,7 +1630,7 @@ def redirect_deactivated_user_to_login(realm: Realm, email: str) -> HttpResponse
 
 
 def social_associate_user_helper(
-    backend: BaseAuth, return_data: dict[str, Any], *args: Any, **kwargs: Any
+    backend: "SocialAuthMixin", return_data: dict[str, Any], *args: Any, **kwargs: Any
 ) -> HttpResponse | UserProfile | None:
     """Responsible for doing the Zulip account lookup and validation parts
     of the Zulip social auth pipeline (similar to the authenticate()
@@ -1790,6 +1790,7 @@ def social_auth_associate_user(
     later stages of settings.SOCIAL_AUTH_PIPELINE, such as
     social_auth_finish, as kwargs.
     """
+    assert isinstance(backend, SocialAuthMixin)
     partial_token = backend.strategy.request_data().get("partial_token")
     return_data: dict[str, Any] = {}
     user_profile = social_associate_user_helper(backend, return_data, *args, **kwargs)
@@ -2143,15 +2144,15 @@ class GitHubAuthBackend(SocialAuthMixin, GithubOAuth2):
                 **kwargs,
             )
         elif team_id is not None:
-            backend = GithubTeamOAuth2(self.strategy, self.redirect_uri)
+            team_backend = GithubTeamOAuth2(self.strategy, self.redirect_uri)
             try:
-                return backend.user_data(access_token, *args, **kwargs)
+                return team_backend.user_data(access_token, *args, **kwargs)
             except AuthFailed:
                 return dict(auth_failed_reason="GitHub user is not member of required team")
         elif org_name is not None:
-            backend = GithubOrganizationOAuth2(self.strategy, self.redirect_uri)
+            organization_backend = GithubOrganizationOAuth2(self.strategy, self.redirect_uri)
             try:
-                return backend.user_data(access_token, *args, **kwargs)
+                return organization_backend.user_data(access_token, *args, **kwargs)
             except AuthFailed:
                 return dict(auth_failed_reason="GitHub user is not member of required organization")