diff --git a/lib/rails_erd/domain/relationship.rb b/lib/rails_erd/domain/relationship.rb
index 5c77f649..951874ba 100644
--- a/lib/rails_erd/domain/relationship.rb
+++ b/lib/rails_erd/domain/relationship.rb
@@ -21,8 +21,7 @@ def from_associations(domain, associations) # @private :nodoc:
         private
 
         def association_identity(association)
-          identifier = association_identifier(association).to_s
-          Set[identifier, association_owner(association), association_target(association)]
+          Set[association_owner(association), association_target(association)]
         end
 
         def association_identifier(association)