diff --git a/changelog.txt b/changelog.txt
index d3a20e31..6456733f 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -46,6 +46,7 @@ OPENSEADRAGON CHANGELOG
 * Added ajaxWithCredentials option (#543)
 * Added viewport-change event for after the viewport changes but before it's drawn
 * A spring's current value is now updated immediately on reset (#524)
+* Fixed an error in fitBounds that occurred sometimes with immediately = true
 
 1.2.1: (in progress)
 
diff --git a/src/viewport.js b/src/viewport.js
index d6fd8606..b6b57e27 100644
--- a/src/viewport.js
+++ b/src/viewport.js
@@ -588,11 +588,17 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
             }
 
             newBounds = this._applyBoundaryConstraints( newBounds, immediately );
+            center = newBounds.getCenter();
+        }
+
+        if (immediately) {
+            this.panTo( center, true );
+            return this.zoomTo(newZoom, null, true);
         }
 
         if (Math.abs(newZoom - oldZoom) < 0.00000000001 ||
                 Math.abs(newBounds.width - oldBounds.width) < 0.00000000001) {
-            return this.panTo( constraints ? newBounds.getCenter() : center, immediately );
+            return this.panTo( center, immediately );
         }
 
         referencePoint = oldBounds.getTopLeft().times(