diff --git a/buffer/src/main/java/io/netty/buffer/CompositeByteBuf.java b/buffer/src/main/java/io/netty/buffer/CompositeByteBuf.java
index dbd69a163b..99127cbd2e 100644
--- a/buffer/src/main/java/io/netty/buffer/CompositeByteBuf.java
+++ b/buffer/src/main/java/io/netty/buffer/CompositeByteBuf.java
@@ -753,7 +753,12 @@ public class CompositeByteBuf extends AbstractReferenceCountedByteBuf implements
                 if (bytesToTrim < cLength) {
                     // Trim the last component
                     c.endOffset -= bytesToTrim;
-                    c.slice = null;
+                    ByteBuf slice = c.slice;
+                    if (slice != null) {
+                        // We must replace the cached slice with a derived one to ensure that
+                        // it can later be released properly in the case of PooledSlicedByteBuf.
+                        c.slice = slice.slice(0, c.length());
+                    }
                     break;
                 }
                 c.free();
@@ -1732,10 +1737,16 @@ public class CompositeByteBuf extends AbstractReferenceCountedByteBuf implements
             }
             firstComponentId++;
         } else {
+            int trimmedBytes = readerIndex - c.offset;
             c.offset = 0;
             c.endOffset -= readerIndex;
             c.adjustment += readerIndex;
-            c.slice = null;
+            ByteBuf slice = c.slice;
+            if (slice != null) {
+                // We must replace the cached slice with a derived one to ensure that
+                // it can later be released properly in the case of PooledSlicedByteBuf.
+                c.slice = slice.slice(trimmedBytes, c.length());
+            }
         }
 
         removeCompRange(0, firstComponentId);
diff --git a/buffer/src/test/java/io/netty/buffer/AbstractCompositeByteBufTest.java b/buffer/src/test/java/io/netty/buffer/AbstractCompositeByteBufTest.java
index e6bebe43ce..ffeebaac9c 100644
--- a/buffer/src/test/java/io/netty/buffer/AbstractCompositeByteBufTest.java
+++ b/buffer/src/test/java/io/netty/buffer/AbstractCompositeByteBufTest.java
@@ -1252,6 +1252,40 @@ public abstract class AbstractCompositeByteBufTest extends AbstractByteBufTest {
         assertEquals(0, b2.refCnt());
     }
 
+    @Test
+    public void testReleasesOnShrink2() {
+        // It is important to use a pooled allocator here to ensure
+        // the slices returned by readRetainedSlice are of type
+        // PooledSlicedByteBuf, which maintains an independent refcount
+        // (so that we can be sure to cover this case)
+        ByteBuf buffer = PooledByteBufAllocator.DEFAULT.buffer();
+
+        buffer.writeShort(1).writeShort(2);
+
+        ByteBuf b1 = buffer.readRetainedSlice(2);
+        ByteBuf b2 = b1.retainedSlice(b1.readerIndex(), 2);
+
+        // composite takes ownership of b1 and b2
+        ByteBuf composite = Unpooled.compositeBuffer()
+            .addComponents(b1, b2);
+
+        assertEquals(4, composite.capacity());
+
+        // reduce capacity down to two, will drop the second component
+        composite.capacity(2);
+        assertEquals(2, composite.capacity());
+
+        // releasing composite should release the components
+        composite.release();
+        assertEquals(0, composite.refCnt());
+        assertEquals(0, b1.refCnt());
+        assertEquals(0, b2.refCnt());
+
+        // release last remaining ref to buffer
+        buffer.release();
+        assertEquals(0, buffer.refCnt());
+    }
+
     @Test
     public void testAllocatorIsSameWhenCopy() {
         testAllocatorIsSameWhenCopy(false);