diff --git a/hutool-core/src/main/java/cn/hutool/core/map/MapUtil.java b/hutool-core/src/main/java/cn/hutool/core/map/MapUtil.java
index e99787edd..3ade23d5f 100755
--- a/hutool-core/src/main/java/cn/hutool/core/map/MapUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/map/MapUtil.java
@@ -1577,7 +1577,7 @@ public class MapUtil {
 	public static <K, V> Map<K, V> flatten(Map<K, V> map) {
 		Assert.notNull(map);
 		Map<K, V> flatMap = new HashMap<>();
-		flatten(map,  flatMap);
+		flatten(map, flatMap);
 		return flatMap;
 	}
 }