diff --git a/codec-http2/src/test/java/io/netty/handler/codec/http2/StreamBufferingEncoderTest.java b/codec-http2/src/test/java/io/netty/handler/codec/http2/StreamBufferingEncoderTest.java
index 3c75c874e9..da55823c79 100644
--- a/codec-http2/src/test/java/io/netty/handler/codec/http2/StreamBufferingEncoderTest.java
+++ b/codec-http2/src/test/java/io/netty/handler/codec/http2/StreamBufferingEncoderTest.java
@@ -15,22 +15,6 @@
 
 package io.netty.handler.codec.http2;
 
-import static io.netty.handler.codec.http2.Http2CodecUtil.DEFAULT_MAX_FRAME_SIZE;
-import static io.netty.handler.codec.http2.Http2CodecUtil.DEFAULT_PRIORITY_WEIGHT;
-import static io.netty.handler.codec.http2.Http2CodecUtil.SMALLEST_MAX_CONCURRENT_STREAMS;
-import static io.netty.handler.codec.http2.Http2Error.CANCEL;
-import static io.netty.handler.codec.http2.Http2Stream.State.HALF_CLOSED_LOCAL;
-import static org.junit.Assert.assertEquals;
-import static org.mockito.Matchers.any;
-import static org.mockito.Matchers.anyInt;
-import static org.mockito.Matchers.anyLong;
-import static org.mockito.Matchers.eq;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.never;
-import static org.mockito.Mockito.times;
-import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.when;
-
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import io.netty.buffer.UnpooledByteBufAllocator;
@@ -49,6 +33,22 @@ import org.mockito.invocation.InvocationOnMock;
 import org.mockito.stubbing.Answer;
 import org.mockito.verification.VerificationMode;
 
+import static io.netty.handler.codec.http2.Http2CodecUtil.DEFAULT_MAX_FRAME_SIZE;
+import static io.netty.handler.codec.http2.Http2CodecUtil.DEFAULT_PRIORITY_WEIGHT;
+import static io.netty.handler.codec.http2.Http2CodecUtil.SMALLEST_MAX_CONCURRENT_STREAMS;
+import static io.netty.handler.codec.http2.Http2Error.CANCEL;
+import static io.netty.handler.codec.http2.Http2Stream.State.HALF_CLOSED_LOCAL;
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Matchers.any;
+import static org.mockito.Matchers.anyInt;
+import static org.mockito.Matchers.anyLong;
+import static org.mockito.Matchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
 /**
  * Tests for {@link StreamBufferingEncoder}.
  */
@@ -417,6 +417,12 @@ public class StreamBufferingEncoderTest {
         return new Answer<ChannelFuture>() {
             @Override
             public ChannelFuture answer(InvocationOnMock invocation) throws Throwable {
+                for (Object a: invocation.getArguments()) {
+                    if (a instanceof ByteBuf) {
+                        ((ByteBuf) a).release();
+                    }
+                }
+
                 ChannelPromise future =
                         new DefaultChannelPromise(channel, ImmediateEventExecutor.INSTANCE);
                 future.setSuccess();