diff --git a/benchmarks/SendPort/dart/SendPort.dart b/benchmarks/SendPort/dart/SendPort.dart
index a6e6044bd9f..fb950b58f30 100644
--- a/benchmarks/SendPort/dart/SendPort.dart
+++ b/benchmarks/SendPort/dart/SendPort.dart
@@ -175,8 +175,11 @@ class SendPortBenchmark {
 }
 
 class TreeNode {
+  @pragma('vm:entry-point') // Prevent tree shaking of this field.
   final TreeNode? left;
+  @pragma('vm:entry-point') // Prevent tree shaking of this field.
   final TreeNode? right;
+  @pragma('vm:entry-point') // Prevent tree shaking of this field.
   final int value;
 
   TreeNode(this.left, this.right, this.value);
diff --git a/benchmarks/SendPort/dart2/SendPort.dart b/benchmarks/SendPort/dart2/SendPort.dart
index 01d40429710..a97acf30f7b 100644
--- a/benchmarks/SendPort/dart2/SendPort.dart
+++ b/benchmarks/SendPort/dart2/SendPort.dart
@@ -177,8 +177,11 @@ class SendPortBenchmark {
 }
 
 class TreeNode {
+  @pragma('vm:entry-point') // Prevent tree shaking of this field.
   final TreeNode left;
+  @pragma('vm:entry-point') // Prevent tree shaking of this field.
   final TreeNode right;
+  @pragma('vm:entry-point') // Prevent tree shaking of this field.
   final int value;
 
   TreeNode(this.left, this.right, this.value);