diff --git a/src/classes/QueryBuilder.cls b/src/classes/QueryBuilder.cls
index d41e4a5..33c2b06 100644
--- a/src/classes/QueryBuilder.cls
+++ b/src/classes/QueryBuilder.cls
@@ -2194,7 +2194,7 @@ public virtual inherited sharing class QueryBuilder {
                 this.formedCondition = '';
                 return this;
             }
-            this.formedCondition = this.fieldName + ' IN ' + this.bracket(builtSubQuery);
+            this.formedCondition = this.fieldName + ' NOT IN ' + this.bracket(builtSubQuery);
             return this;
         }
     }
@@ -2662,4 +2662,4 @@ public virtual inherited sharing class QueryBuilder {
 
     public class QueryBuilderException extends Exception {
     }
-}
\ No newline at end of file
+}