diff --git a/tool/templates/dart/init.dart b/tool/templates/dart/init.dart
index 2c07bce6d..6f799c8cc 100644
--- a/tool/templates/dart/init.dart
+++ b/tool/templates/dart/init.dart
@@ -304,8 +304,7 @@ class _FinalizedArena {
     _finalizer.attach(this, this.arena);
   }
   // Construct
-  _FinalizedArena.withLifetime(core.List<core.List<Object>> lifetimeAppendArray) : this.arena = ffi2.Arena() {
-    _finalizer.attach(this, this.arena);
+  _FinalizedArena.withLifetime(core.List<core.List<Object>> lifetimeAppendArray) : this() {
     for (final edge in lifetimeAppendArray) {
       edge.add(this);
     }