diff --git a/spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/grape/CompositeProxySelector.java b/spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/grape/CompositeProxySelector.java
index 76182d6733..45655930d7 100644
--- a/spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/grape/CompositeProxySelector.java
+++ b/spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/grape/CompositeProxySelector.java
@@ -30,7 +30,7 @@ import org.eclipse.aether.repository.RemoteRepository;
  */
 public class CompositeProxySelector implements ProxySelector {
 
-	private List<ProxySelector> selectors;
+	private final List<ProxySelector> selectors;
 
 	public CompositeProxySelector(List<ProxySelector> selectors) {
 		this.selectors = selectors;