diff --git a/lib/perpetuity/mongodb/query_expression.rb b/lib/perpetuity/mongodb/query_expression.rb
index <HASH>..<HASH> 100644
--- a/lib/perpetuity/mongodb/query_expression.rb
+++ b/lib/perpetuity/mongodb/query_expression.rb
@@ -16,7 +16,7 @@ module Perpetuity
       end
 
       def to_db
-        send @comparator
+        public_send @comparator
       end
 
       def equals
Prefer public_send over send