diff --git a/common/predictive-text/index.ts b/common/predictive-text/index.ts
index 3aa1c61117..93e2ada8ba 100644
--- a/common/predictive-text/index.ts
+++ b/common/predictive-text/index.ts
@@ -23,7 +23,6 @@
 /// <reference path="node_modules/es6-shim/es6-shim.min.js" />
 /// <reference path="promise-store.ts" />
 /// <reference path="lmlayer-interface.ts" />
-/// <reference path="web-workerFactory.ts" />
 
 /**
  * Top-level interface to the Language Modelling layer, or "LMLayer" for short.
@@ -53,8 +52,9 @@ namespace com.keyman.text.prediction {
      * @param uri URI of the underlying LMLayer worker code. This will usually be a blob:
      *            or file: URI. If uri is not provided, this will start the default Worker.
      */
-    constructor(capabilities: Capabilities) {
-      super(capabilities, new WebWorkerFactory());
+    constructor(capabilities: Capabilities, worker?: Worker) {
+      worker = worker || DefaultWorker.constructInstance();
+      super(capabilities, worker);
     }
   }
 }
diff --git a/common/predictive-text/lmlayer-interface.ts b/common/predictive-text/lmlayer-interface.ts
index 47a8a8d5c5..18a47b5551 100644
--- a/common/predictive-text/lmlayer-interface.ts
+++ b/common/predictive-text/lmlayer-interface.ts
@@ -1,5 +1,3 @@
-///<reference path="workerFactory.ts" />
-
 namespace com.keyman.text.prediction {
   export abstract class LMLayerBase {
     /**
@@ -19,9 +17,9 @@ namespace com.keyman.text.prediction {
      * @param uri URI of the underlying LMLayer worker code. This will usually be a blob:
      *            or file: URI. If uri is not provided, this will start the default Worker.
      */
-    constructor(capabilities: Capabilities, workerFactory: WorkerFactory) {
+    constructor(capabilities: Capabilities, worker: Worker) {
       // Either use the given worker, or instantiate the default worker.
-      this._worker = workerFactory.constructInstance();
+      this._worker = worker;
       this._worker.onmessage = this.onMessage.bind(this)
       this._declareLMLayerReady = null;
       this._predictPromises = new PromiseStore;
diff --git a/common/predictive-text/unit_tests/headless/top-level-lmlayer.js b/common/predictive-text/unit_tests/headless/top-level-lmlayer.js
index de8351fd10..dfad22e730 100644
--- a/common/predictive-text/unit_tests/headless/top-level-lmlayer.js
+++ b/common/predictive-text/unit_tests/headless/top-level-lmlayer.js
@@ -9,14 +9,14 @@ let LMLayerBase = LMLayer.LMLayerBase;
 describe('LMLayer', function() {
   describe('[[constructor]]', function () {
     it('should accept a Worker to instantiate', function () {
-      new LMLayerBase(capabilities(), createFakeWorkerFactory());
+      new LMLayerBase(capabilities(), createFakeWorker());
     });
 
     it('should send the `config` message to the LMLayer', async function () {
-      let fakeWorker = createFakeWorkerFactory(fakePostMessage);
+      let fakeWorker = createFakeWorker(fakePostMessage);
       let lmLayer = new LMLayerBase(capabilities(), fakeWorker);
 
-      assert.propertyVal(fakeWorker.instance.postMessage, 'callCount', 1);
+      assert.propertyVal(fakeWorker.postMessage, 'callCount', 1);
       // In the "Worker", assert the message looks right
       function fakePostMessage(data) {
         assert.propertyVal(data, 'message', 'config');
@@ -27,20 +27,20 @@ describe('LMLayer', function() {
 
   describe('#loadModel()', function () {
     it('should accept capabilities and model description', function () {
-      let fakeWorker = createFakeWorkerFactory();
+      let fakeWorker = createFakeWorker();
 
       let lmLayer = new LMLayerBase(capabilities(), fakeWorker);
       lmLayer.loadModel("./unit_tests/in_browser/resources/models/simple-dummy.js");
 
-      assert.isFunction(fakeWorker.instance.onmessage, 'LMLayer failed to set a callback!');
+      assert.isFunction(fakeWorker.onmessage, 'LMLayer failed to set a callback!');
     });
 
     it('should send the `load` message to the LMLayer', async function () {
-      let fakeWorker = createFakeWorkerFactory(fakePostMessage);
+      let fakeWorker = createFakeWorker(fakePostMessage);
       let lmLayer = new LMLayerBase(capabilities(), fakeWorker);
       let configuration = await lmLayer.loadModel("./unit_tests/in_browser/resources/models/simple-dummy.js");
 
-      assert.propertyVal(fakeWorker.instance.postMessage, 'callCount', 2);
+      assert.propertyVal(fakeWorker.postMessage, 'callCount', 2);
       // In the "Worker", assert the message looks right and
       // ASYNCHRONOUSLY reply with ready message.
       function fakePostMessage(data) {
@@ -52,7 +52,7 @@ describe('LMLayer', function() {
         assert.propertyVal(data, 'message', 'load');
         assert.isString(data.model);
       
-        callAsynchronously(() => fakeWorker.instance.onmessage({
+        callAsynchronously(() => fakeWorker.onmessage({
           data: {
             message: 'ready',
             configuration: {}
@@ -67,8 +67,8 @@ describe('LMLayer', function() {
         rightContextCodeUnits: 0,
       }
 
-      let fakeWorker = createFakeWorkerFactory(function fakePostMessage(_data) {
-        callAsynchronously(() => fakeWorker.instance.onmessage({
+      let fakeWorker = createFakeWorker(function fakePostMessage(_data) {
+        callAsynchronously(() => fakeWorker.onmessage({
           data: {
             message: 'ready',
             configuration: expectedConfiguration
@@ -114,17 +114,11 @@ describe('LMLayer', function() {
    * 
    * @returns {WorkerFactory} a 'factory' class returning a Worker object with sinon.fake() instances.
    */
-  function createFakeWorkerFactory(postMessage) {
-    let FakeFactory = function() {}; // barebones JS class definition - requires function as core, constructor.
-    FakeFactory.prototype.constructInstance = function() {
-      this.instance = {
-        postMessage: postMessage ? sinon.fake(postMessage) : sinon.fake(),
-        onmessage: null
-      };
-
-      return this.instance;
+  function createFakeWorker(postMessage) {
+    return {
+      postMessage: postMessage ? sinon.fake(postMessage) : sinon.fake(),
+      onmessage: null
     };
-    return new FakeFactory();
   }
 
   /**
diff --git a/common/predictive-text/web-workerFactory.ts b/common/predictive-text/web-defaultWorker.ts
similarity index 78%
rename from common/predictive-text/web-workerFactory.ts
rename to common/predictive-text/web-defaultWorker.ts
index aa230d82e7..6a4f527c13 100644
--- a/common/predictive-text/web-workerFactory.ts
+++ b/common/predictive-text/web-defaultWorker.ts
@@ -1,9 +1,7 @@
-/// <reference path="workerFactory.ts" />
-
 namespace com.keyman.text.prediction {
-  export class WebWorkerFactory implements WorkerFactory {
-    constructInstance(): Worker {
-      return new Worker(WebWorkerFactory.asBlobURI(LMLayerWorkerCode));
+  export class DefaultWorker {
+    static constructInstance(): Worker {
+      return new Worker(this.asBlobURI(LMLayerWorkerCode));
     }
     
     /**
diff --git a/common/predictive-text/workerFactory.ts b/common/predictive-text/workerFactory.ts
deleted file mode 100644
index f80e820364..0000000000
--- a/common/predictive-text/workerFactory.ts
+++ /dev/null
@@ -1,5 +0,0 @@
-namespace com.keyman.text.prediction {
-  export interface WorkerFactory {
-    constructInstance(): Worker;
-  }
-}
\ No newline at end of file
diff --git a/web/source/includes/lmlayer.ts b/web/source/includes/lmlayer.ts
index e34f8c6d21..5a60c03e8f 100644
--- a/web/source/includes/lmlayer.ts
+++ b/web/source/includes/lmlayer.ts
@@ -4,6 +4,7 @@
 
 // Defines the main interface of the Language Modeling Layer (LMLayer) and its original typing information.
 ///<reference path="../../../common/predictive-text/embedded_worker.d.ts" />
+///<reference path="../../../common/predictive-text/web-defaultWorker.ts" />
 ///<reference path="../../../common/predictive-text/index.ts" />
 
 // We DO need the embedded_worker.d.ts file - since we're directly linking into the LMLayer's code,