diff --git a/social_core/pipeline/social_auth.py b/social_core/pipeline/social_auth.py
index 1fd124aff..1c5940e75 100644
--- a/social_core/pipeline/social_auth.py
+++ b/social_core/pipeline/social_auth.py
@@ -6,7 +6,7 @@ def social_details(backend, details, response, *args, **kwargs):
 
 
 def social_uid(backend, details, response, *args, **kwargs):
-    return {"uid": backend.get_user_id(details, response)}
+    return {"uid": str(backend.get_user_id(details, response))}
 
 
 def auth_allowed(backend, details, response, *args, **kwargs):
diff --git a/social_core/tests/backends/test_bitbucket_datacenter.py b/social_core/tests/backends/test_bitbucket_datacenter.py
index 8a3d3f9c5..dda5fbb6f 100644
--- a/social_core/tests/backends/test_bitbucket_datacenter.py
+++ b/social_core/tests/backends/test_bitbucket_datacenter.py
@@ -83,7 +83,7 @@ def test_login(self):
         self.assertEqual(len(user.social), 1)
 
         social = user.social[0]
-        self.assertEqual(social.uid, 1)
+        self.assertEqual(social.uid, "1")
         self.assertEqual(social.extra_data["first_name"], "Erlich")
         self.assertEqual(social.extra_data["last_name"], "Bachman")
         self.assertEqual(social.extra_data["email"], "erlich@bachmanity.com")
@@ -109,7 +109,7 @@ def test_login(self):
     def test_refresh_token(self):
         _, social = self.do_refresh_token()
 
-        self.assertEqual(social.uid, 1)
+        self.assertEqual(social.uid, "1")
         self.assertEqual(social.extra_data["first_name"], "Erlich")
         self.assertEqual(social.extra_data["last_name"], "Bachman")
         self.assertEqual(social.extra_data["email"], "erlich@bachmanity.com")