diff --git a/web/ui_utils.js b/web/ui_utils.js
index c067dd420d3de..7c615f2f82247 100644
--- a/web/ui_utils.js
+++ b/web/ui_utils.js
@@ -13,8 +13,6 @@
  * limitations under the License.
  */
 
-import { createPromiseCapability } from 'pdfjs-lib';
-
 const CSS_UNITS = 96.0 / 72.0;
 const DEFAULT_SCALE_VALUE = 'auto';
 const DEFAULT_SCALE = 1.0;
@@ -634,37 +632,35 @@ const WaitOnType = {
  * @returns {Promise} A promise that is resolved with a {WaitOnType} value.
  */
 function waitOnEventOrTimeout({ target, name, delay = 0, }) {
-  if (typeof target !== 'object' || !(name && typeof name === 'string') ||
-      !(Number.isInteger(delay) && delay >= 0)) {
-    return Promise.reject(
-      new Error('waitOnEventOrTimeout - invalid parameters.'));
-  }
-  let capability = createPromiseCapability();
-
-  function handler(type) {
-    if (target instanceof EventBus) {
-      target.off(name, eventHandler);
-    } else {
-      target.removeEventListener(name, eventHandler);
+  return new Promise(function(resolve, reject) {
+    if (typeof target !== 'object' || !(name && typeof name === 'string') ||
+        !(Number.isInteger(delay) && delay >= 0)) {
+      throw new Error('waitOnEventOrTimeout - invalid parameters.');
     }
 
-    if (timeout) {
-      clearTimeout(timeout);
-    }
-    capability.resolve(type);
-  }
+    function handler(type) {
+      if (target instanceof EventBus) {
+        target.off(name, eventHandler);
+      } else {
+        target.removeEventListener(name, eventHandler);
+      }
 
-  let eventHandler = handler.bind(null, WaitOnType.EVENT);
-  if (target instanceof EventBus) {
-    target.on(name, eventHandler);
-  } else {
-    target.addEventListener(name, eventHandler);
-  }
+      if (timeout) {
+        clearTimeout(timeout);
+      }
+      resolve(type);
+    }
 
-  let timeoutHandler = handler.bind(null, WaitOnType.TIMEOUT);
-  let timeout = setTimeout(timeoutHandler, delay);
+    const eventHandler = handler.bind(null, WaitOnType.EVENT);
+    if (target instanceof EventBus) {
+      target.on(name, eventHandler);
+    } else {
+      target.addEventListener(name, eventHandler);
+    }
 
-  return capability.promise;
+    const timeoutHandler = handler.bind(null, WaitOnType.TIMEOUT);
+    let timeout = setTimeout(timeoutHandler, delay);
+  });
 }
 
 /**