diff --git a/src/checkstyle/com/puppycrawl/tools/checkstyle/api/DetailAST.java b/src/checkstyle/com/puppycrawl/tools/checkstyle/api/DetailAST.java
index d250c1139..3ac0cf64a 100644
--- a/src/checkstyle/com/puppycrawl/tools/checkstyle/api/DetailAST.java
+++ b/src/checkstyle/com/puppycrawl/tools/checkstyle/api/DetailAST.java
@@ -31,7 +31,7 @@ import antlr.collections.AST;
  * @author lkuehne
  * @version 1.0
  */
-public class DetailAST
+public final class DetailAST
     extends CommonAST
 {
     /** constant to indicate if not calculated the child count */