diff --git a/core/api/serializers/custom/__init__.py b/core/api/serializers/custom/__init__.py
index 5c78f3a9..68d8ac17 100644
--- a/core/api/serializers/custom/__init__.py
+++ b/core/api/serializers/custom/__init__.py
@@ -70,7 +70,7 @@ class Meta:
 
     @staticmethod
     def get_gravatar_url(obj: User):
-        return gravatar_url(obj.email_user())
+        return gravatar_url(str(obj))
 
 
 class OrganizationSerializer(serializers.ModelSerializer):