diff --git a/src/core/worker.js b/src/core/worker.js
index 262a29048338c..a905efe27a8c8 100644
--- a/src/core/worker.js
+++ b/src/core/worker.js
@@ -364,6 +364,15 @@ var WorkerMessageHandler = {
     var cancelXHRs = null;
     var WorkerTasks = [];
 
+    let apiVersion = docParams.apiVersion;
+    let workerVersion =
+      typeof PDFJSDev !== 'undefined' ? PDFJSDev.eval('BUNDLE_VERSION') : null;
+    // The `apiVersion !== null` check is needed to avoid errors during testing.
+    if (apiVersion !== null && apiVersion !== workerVersion) {
+      throw new Error(`The API version "${apiVersion}" does not match ` +
+                      `the Worker version "${workerVersion}".`);
+    }
+
     var docId = docParams.docId;
     var docBaseUrl = docParams.docBaseUrl;
     var workerHandlerName = docParams.docId + '_worker';
diff --git a/src/display/api.js b/src/display/api.js
index ec08f8204114d..63bb9fc850058 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -331,6 +331,8 @@ function _fetchDocument(worker, source, pdfDataRangeTransport, docId) {
   if (worker.destroyed) {
     return Promise.reject(new Error('Worker was destroyed'));
   }
+  let apiVersion =
+    typeof PDFJSDev !== 'undefined' ? PDFJSDev.eval('BUNDLE_VERSION') : null;
 
   source.disableAutoFetch = getDefaultSetting('disableAutoFetch');
   source.disableStream = getDefaultSetting('disableStream');
@@ -341,6 +343,7 @@ function _fetchDocument(worker, source, pdfDataRangeTransport, docId) {
   }
   return worker.messageHandler.sendWithPromise('GetDocRequest', {
     docId,
+    apiVersion,
     source: {
       data: source.data,
       url: source.url,