diff --git a/web/page_view.js b/web/page_view.js
index 6b88a8f1..ddb30220 100644
--- a/web/page_view.js
+++ b/web/page_view.js
@@ -371,7 +371,7 @@ var PageView = function pageView(container, id, scale,
           width / CSS_UNITS;
         heightScale = (PDFView.container.clientHeight - SCROLLBAR_PADDING) /
           height / CSS_UNITS;
-        scale = Math.min(widthScale, heightScale);
+        scale = Math.min(Math.abs(widthScale), Math.abs(heightScale));
         break;
       default:
         return;
diff --git a/web/viewer.js b/web/viewer.js
index 064a975a..0daf7f93 100644
--- a/web/viewer.js
+++ b/web/viewer.js
@@ -209,7 +209,7 @@ var PDFView = {
     var number = parseFloat(value);
     var scale;
 
-    if (number) {
+    if (number > 0) {
       scale = number;
       resetAutoSettings = true;
     } else {