diff --git a/src/worker/media_source_interface.ts b/src/worker/media_source_interface.ts
index 9e76185ecf..3caeca819d 100644
--- a/src/worker/media_source_interface.ts
+++ b/src/worker/media_source_interface.ts
@@ -185,18 +185,27 @@ export class SourceBufferInterface extends EventEmitter<ISourceBufferInterfaceEv
       sourceBuffer.appendBuffer(data);
       return;
     } else {
-      const abData = data instanceof ArrayBuffer ?
-        data :
-        data.buffer;
+      // TODO are we forced to copy here?
+      let segmentBufferPushed : ArrayBuffer;
+      if (data instanceof ArrayBuffer) {
+        segmentBufferPushed = data;
+      } else if (data.byteLength === data.buffer.byteLength) {
+        segmentBufferPushed = data.buffer;
+      } else {
+        segmentBufferPushed = data.buffer.slice(
+          data.byteOffset,
+          data.byteLength + data.byteOffset
+        );
+      }
       sendMessage({
         type: "append-buffer",
         mediaSourceId: this._state.mediaSourceId,
         sourceBufferType: this.type,
         value: {
-          data: abData,
+          data: segmentBufferPushed,
           params,
         },
-      }, [abData]);
+      }, [segmentBufferPushed]);
     }
   }
 
diff --git a/src/worker/send_message.ts b/src/worker/send_message.ts
index 32853a8700..a9b1015587 100644
--- a/src/worker/send_message.ts
+++ b/src/worker/send_message.ts
@@ -22,8 +22,7 @@ export default function sendMessage(
   } else {
     // TypeScript made a mistake here, and 2busy2fix
     /* eslint-disable-next-line */
-    // XXX TODO add transferables urgently
-    (postMessage as any)(msg);
+    (postMessage as any)(msg, transferables);
   }
 }