diff --git a/spring-core/src/main/java/org/springframework/util/StreamUtils.java b/spring-core/src/main/java/org/springframework/util/StreamUtils.java
index 0fe41fcde08..de59989eb1f 100644
--- a/spring-core/src/main/java/org/springframework/util/StreamUtils.java
+++ b/spring-core/src/main/java/org/springframework/util/StreamUtils.java
@@ -127,6 +127,7 @@ public abstract class StreamUtils {
 		Assert.notNull(out, "No OutputStream specified");
 
 		out.write(in);
+		out.flush();
 	}
 
 	/**