diff --git a/activerecord/lib/active_record/associations/association_proxy.rb b/activerecord/lib/active_record/associations/association_proxy.rb
index ec16af38973a0..11c64243a2ccf 100644
--- a/activerecord/lib/active_record/associations/association_proxy.rb
+++ b/activerecord/lib/active_record/associations/association_proxy.rb
@@ -210,7 +210,8 @@ def foreign_key_present
 
         def raise_on_type_mismatch(record)
           unless record.is_a?(@reflection.klass)
-            raise ActiveRecord::AssociationTypeMismatch, "#{@reflection.klass} expected, got #{record.class}"
+            message = "#{@reflection.class_name}(##{@reflection.klass.object_id}) expected, got #{record.class}(##{record.class.object_id})"
+            raise ActiveRecord::AssociationTypeMismatch, message
           end
         end