diff --git a/codec-http/src/main/java/io/netty/handler/codec/http/multipart/InternalAttribute.java b/codec-http/src/main/java/io/netty/handler/codec/http/multipart/InternalAttribute.java
index fead2adedc..275b46aeea 100644
--- a/codec-http/src/main/java/io/netty/handler/codec/http/multipart/InternalAttribute.java
+++ b/codec-http/src/main/java/io/netty/handler/codec/http/multipart/InternalAttribute.java
@@ -32,7 +32,7 @@ final class InternalAttribute extends AbstractReferenceCounted implements Interf
     private final Charset charset;
     private int size;
 
-    public InternalAttribute(Charset charset) {
+    InternalAttribute(Charset charset) {
         this.charset = charset;
     }
 
@@ -67,6 +67,7 @@ final class InternalAttribute extends AbstractReferenceCounted implements Interf
         ByteBuf old = this.value.set(rank, buf);
         if (old != null) {
             size -= old.readableBytes();
+            old.release();
         }
         size += buf.readableBytes();
     }