diff --git a/src/viewer.js b/src/viewer.js
index 8ebbd2b3..55c4cce9 100644
--- a/src/viewer.js
+++ b/src/viewer.js
@@ -1107,6 +1107,17 @@ $.extend( $.Viewer.prototype, $.EventHandler.prototype, $.ControlDock.prototype,
     }
 });
 
+
+/**
+ * [_getSafeElemSize returns getElementSize(), but refuses to return NaN]
+ * @return {[NaN]}
+ * @private
+ */
+function _getSafeElemSize () {
+        var _nElementSize = $.getElementSize();
+        return isNaN(_nElementSize) ? 0 : _nElementSize;
+}
+
 /**
  * @function
  * @private
@@ -1121,7 +1132,7 @@ function openTileSource( viewer, source ) {
     }
 
     _this.canvas.innerHTML = "";
-    THIS[ _this.hash ].prevContainerSize = $.getElementSize( _this.container );
+    THIS[ _this.hash ].prevContainerSize = $._getSafeElemSize( _this.container );
 
 
     if( _this.collectionMode ){
@@ -1514,7 +1525,7 @@ function updateOnce( viewer ) {
 
     //viewer.profiler.beginUpdate();
 
-    containerSize = $.getElementSize( viewer.container );
+    containerSize = $._getSafeElemSize( viewer.container );
     if ( !containerSize.equals( THIS[ viewer.hash ].prevContainerSize ) ) {
         // maintain image position
         viewer.viewport.resize( containerSize, true );