diff --git a/archive/archive-internal.js b/archive/archive-internal.js
index 446b5b2..063a9c3 100644
--- a/archive/archive-internal.js
+++ b/archive/archive-internal.js
@@ -41,20 +41,20 @@ export const UnarchiveEventType = {
 }
 
 /**
- * Updates all Archiver listeners with the updated bytes.
+ * Updates all Archiver listeners that an append has occurred.
  */
  export class UnarchiveAppendEvent extends UnarchiveEvent {
   /**
-   * @param {ArrayBuffer} ab The new bytes
+   * @param {number} numBytes The number of bytes appended.
    */
-  constructor(ab) {
+  constructor(numBytes) {
     super(UnarchiveEventType.APPEND);
 
     /**
-     * The appended bytes.
-     * @type {ArrayBuffer}
+     * The number of appended bytes.
+     * @type {number}
      */
-    this.ab = ab;
+    this.numBytes = numBytes;
   }
 }
 
@@ -169,7 +169,9 @@ export class UnarchiveExtractEvent extends UnarchiveEvent {
  */
  export class Unarchiver {
   /**
-   * @param {ArrayBuffer} arrayBuffer The Array Buffer.
+   * @param {ArrayBuffer} arrayBuffer The Array Buffer. Note that this ArrayBuffer must not be
+   *     referenced once it is sent to the Unarchiver, since it is marked as Transferable and sent
+   *     to the Worker.
    * @param {Function(string):Worker} createWorkerFn A function that creates a Worker from a script file.
    * @param {Object|string} options An optional object of options, or a string representing where
    *     the BitJS files are located.  The string version of this argument is deprecated.
@@ -349,7 +351,7 @@ export class UnarchiveExtractEvent extends UnarchiveEvent {
       this.worker_.postMessage({
         file: ab,
         logToConsole: this.debugMode_,
-      });
+      }, [ab]);
       this.ab = null;
     }
   }
@@ -358,14 +360,25 @@ export class UnarchiveExtractEvent extends UnarchiveEvent {
 
   /**
    * Adds more bytes to the unarchiver's Worker thread.
-   * @param {ArrayBuffer} ab The ArrayBuffer with more bytes in it.
+   * @param {ArrayBuffer} ab The ArrayBuffer with more bytes in it. If opt_transferable is
+   *     set to true, this ArrayBuffer must not be referenced after calling update(), since it
+   *     is marked as Transferable and sent to the Worker.
+   * @param {boolean=} opt_transferable Optional boolean whether to mark this ArrayBuffer
+   *     as a Tranferable object, which means it can no longer be referenced outside of
+   *     the Worker thread.
    */
-  update(ab) {
+  update(ab, opt_transferable = false) {
+    const numBytes = ab.byteLength;
     if (this.worker_) {
-      this.worker_.postMessage({ bytes: ab });
+      // Send the ArrayBuffer over, and mark it as a Transferable object if necessary.
+      if (opt_transferable) {
+        this.worker_.postMessage({ bytes: ab }, [ab]);
+      } else {
+        this.worker_.postMessage({ bytes: ab });
+      }
     }
     if (this.listeners_[UnarchiveEventType.APPEND]) {
-      const evt = new UnarchiveAppendEvent(ab);
+      const evt = new UnarchiveAppendEvent(numBytes);
       this.listeners_[UnarchiveEventType.APPEND].forEach(listener => listener(evt));
     }
   }
diff --git a/archive/archive.js b/archive/archive.js
index ad57978..cd88395 100644
--- a/archive/archive.js
+++ b/archive/archive.js
@@ -30,12 +30,12 @@ export {
 /**
  * All extracted files returned by an Unarchiver will implement
  * the following interface:
- *
- * interface UnarchivedFile {
- *   string filename
- *   TypedArray fileData
- * }
- *
+ */
+
+/**
+ * @typedef UnarchivedFile
+ * @property {string} filename
+ * @property {Uint8Array} fileData
  */
 
 /**
@@ -72,7 +72,9 @@ export class Untarrer extends UntarrerInternal {
 /**
  * Factory method that creates an unarchiver based on the byte signature found
  * in the arrayBuffer.
- * @param {ArrayBuffer} ab
+ * @param {ArrayBuffer} ab The ArrayBuffer to unarchive. Note that this ArrayBuffer
+ *     must not be referenced after calling this method, as the ArrayBuffer is marked
+ *     as Transferable and sent to a Worker thread once start() is called.
  * @param {Object|string} options An optional object of options, or a string
  *     representing where the path to the unarchiver script files.
  * @return {Unarchiver}
diff --git a/archive/unzip.js b/archive/unzip.js
index 484c2ee..d6c9608 100644
--- a/archive/unzip.js
+++ b/archive/unzip.js
@@ -109,6 +109,7 @@ class ZipLocalFile {
     }
 
     // Read in the compressed data if we have no data descriptor.
+    /** @type {Uint8Array} */
     this.fileData = null;
     let descriptorSize = 0;
     if (this.hasDataDescriptor) {
@@ -622,7 +623,7 @@ function archiveUnzip() {
       oneLocalFile.unzip();
 
       if (oneLocalFile.fileData != null) {
-        postMessage({ type: 'extract', unarchivedFile: oneLocalFile });
+        postMessage({ type: 'extract', unarchivedFile: oneLocalFile }, [oneLocalFile.fileData.buffer]);
         postProgress();
       }
     }