diff --git a/lib/ontologies_linked_data/models/users/oauth_authentication.rb b/lib/ontologies_linked_data/models/users/oauth_authentication.rb
index ac4bdf0a..d4f4ec75 100644
--- a/lib/ontologies_linked_data/models/users/oauth_authentication.rb
+++ b/lib/ontologies_linked_data/models/users/oauth_authentication.rb
@@ -70,7 +70,7 @@ def auth_create_user(user_data)
           end
 
           def user_by_email(email)
-            LinkedData::Models::User.where(email: email).first
+            LinkedData::Models::User.where(email: email).first unless email.nil?
           end
 
           def user_from_orcid_data(user_data)