diff --git a/web/app.js b/web/app.js
index 7d40346dd..f2a6a024d 100644
--- a/web/app.js
+++ b/web/app.js
@@ -977,7 +977,7 @@ let PDFViewerApplication = {
             !initialParams.hash) {
           return;
         }
-        if (this.hasEqualPageSizes) {
+        if (pdfViewer.hasEqualPageSizes) {
           return;
         }
         this.initialDestination = initialParams.destination;
@@ -1217,19 +1217,6 @@ let PDFViewerApplication = {
     }
   },
 
-  // Whether all pages of the PDF have the same width and height.
-  get hasEqualPageSizes() {
-    let firstPage = this.pdfViewer.getPageView(0);
-    for (let i = 1, ii = this.pagesCount; i < ii; ++i) {
-      let pageView = this.pdfViewer.getPageView(i);
-      if (pageView.width !== firstPage.width ||
-          pageView.height !== firstPage.height) {
-        return false;
-      }
-    }
-    return true;
-  },
-
   afterPrint: function pdfViewSetupAfterPrint() {
     if (this.printService) {
       this.printService.destroy();
diff --git a/web/pdf_viewer.js b/web/pdf_viewer.js
index 7ec4963f4..9902f5fc2 100644
--- a/web/pdf_viewer.js
+++ b/web/pdf_viewer.js
@@ -914,6 +914,22 @@ var PDFViewer = (function pdfViewer() {
       this.findController = findController;
     },
 
+    /**
+     * @returns {boolean} Whether all pages of the PDF document have identical
+     *                    widths and heights.
+     */
+    get hasEqualPageSizes() {
+      let firstPageView = this._pages[0];
+      for (let i = 1, ii = this._pages.length; i < ii; ++i) {
+        let pageView = this._pages[i];
+        if (pageView.width !== firstPageView.width ||
+            pageView.height !== firstPageView.height) {
+          return false;
+        }
+      }
+      return true;
+    },
+
     /**
      * Returns sizes of the pages.
      * @returns {Array} Array of objects with width/height/rotation fields.