diff --git a/hutool-core/src/main/java/cn/hutool/core/stream/CollectorUtil.java b/hutool-core/src/main/java/cn/hutool/core/stream/CollectorUtil.java
index 8e4001df4..e41e9b84f 100644
--- a/hutool-core/src/main/java/cn/hutool/core/stream/CollectorUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/stream/CollectorUtil.java
@@ -114,7 +114,8 @@ public class CollectorUtil {
 		if (downstream.characteristics().contains(Collector.Characteristics.IDENTITY_FINISH)) {
 			return new SimpleCollector<>(mangledFactory, accumulator, merger, CH_ID);
 		} else {
-			UnaryOperator<A> downstreamFinisher = (UnaryOperator<A>) downstream.finisher();
+			@SuppressWarnings("unchecked")
+			Function<A, A> downstreamFinisher = (Function<A, A>) downstream.finisher();
 			Function<Map<K, A>, M> finisher = intermediate -> {
 				intermediate.replaceAll((k, v) -> downstreamFinisher.apply(v));
 				@SuppressWarnings("unchecked")