diff --git a/web/app.js b/web/app.js
index 6446aa986..23179622c 100644
--- a/web/app.js
+++ b/web/app.js
@@ -1526,11 +1526,12 @@ function webViewerInitialized() {
   });
 
   appConfig.toolbar.pageNumber.addEventListener('change', function() {
-    // Handle the user inputting a floating point number.
     PDFViewerApplication.page = (this.value | 0);
 
-    if (this.value !== (this.value | 0).toString()) {
-      this.value = PDFViewerApplication.page;
+    // Ensure that the page number input displays the correct value, even if the
+    // value entered by the user was invalid (e.g. a floating point number).
+    if (this.value !== PDFViewerApplication.page.toString()) {
+      PDFViewerApplication._updateUIToolbar({});
     }
   });
 
@@ -1971,8 +1972,8 @@ function webViewerPageChanging(e) {
   PDFViewerApplication._updateUIToolbar({
     pageNumber: page,
   });
-  if (e.previousPageNumber !== page &&
-      PDFViewerApplication.pdfSidebar.isThumbnailViewVisible) {
+
+  if (PDFViewerApplication.pdfSidebar.isThumbnailViewVisible) {
     PDFViewerApplication.pdfThumbnailViewer.scrollThumbnailIntoView(page);
   }
 
diff --git a/web/dom_events.js b/web/dom_events.js
index 80893f52a..ae580eb70 100644
--- a/web/dom_events.js
+++ b/web/dom_events.js
@@ -53,7 +53,6 @@
       var event = document.createEvent('UIEvents');
       event.initUIEvent('pagechange', true, true, window, 0);
       event.pageNumber = e.pageNumber;
-      event.previousPageNumber = e.previousPageNumber;
       e.source.container.dispatchEvent(event);
     });
     eventBus.on('pagesinit', function (e) {
diff --git a/web/pdf_viewer.js b/web/pdf_viewer.js
index 0207c6f78..50c69621f 100644
--- a/web/pdf_viewer.js
+++ b/web/pdf_viewer.js
@@ -166,6 +166,9 @@ var PDFViewer = (function pdfViewer() {
      * @param {number} val - The page number.
      */
     set currentPageNumber(val) {
+      if ((val | 0) !== val) { // Ensure that `val` is an integer.
+        throw new Error('Invalid page number.');
+      }
       if (!this.pdfDocument) {
         this._currentPageNumber = val;
         return;
@@ -185,22 +188,14 @@ var PDFViewer = (function pdfViewer() {
         }
         return;
       }
-      var arg;
+
       if (!(0 < val && val <= this.pagesCount)) {
-        arg = {
-          source: this,
-          pageNumber: this._currentPageNumber,
-          previousPageNumber: val
-        };
-        this.eventBus.dispatch('pagechanging', arg);
-        this.eventBus.dispatch('pagechange', arg);
         return;
       }
 
-      arg = {
+      var arg = {
         source: this,
         pageNumber: val,
-        previousPageNumber: this._currentPageNumber
       };
       this._currentPageNumber = val;
       this.eventBus.dispatch('pagechanging', arg);
@@ -223,7 +218,7 @@ var PDFViewer = (function pdfViewer() {
      * @param {number} val - Scale of the pages in percents.
      */
     set currentScale(val) {
-      if (isNaN(val))  {
+      if (isNaN(val)) {
         throw new Error('Invalid numeric scale');
       }
       if (!this.pdfDocument) {