diff --git a/lib/OpenLayers/Map.js b/lib/OpenLayers/Map.js
index bde8169ede..f1bbab3892 100644
--- a/lib/OpenLayers/Map.js
+++ b/lib/OpenLayers/Map.js
@@ -662,6 +662,7 @@ OpenLayers.Map = OpenLayers.Class({
              * be properly set below.
              */
             delete this.center;
+            delete this.zoom;
             this.addLayers(options.layers);
             // set center (and optionally zoom)
             if (options.center && !this.getCenter()) {