diff --git a/js/index.js b/js/index.js
index 9d7ffde..eb69409 100644
--- a/js/index.js
+++ b/js/index.js
@@ -263,10 +263,18 @@
             }
         };
 
+        var onInvalidHashChangeCb = function(params) {
+            params = params.replace('zoom=', 'map=');
+            params = params.replace('&lat=', '/');
+            params = params.replace('&lon=', '/');
+            params = params.replace('&layer=', '/');
+            return params;
+        };
+
         urlHash = new L.Hash(map, mapLayers, function() {
             var url = router.getUrl(routing.getWaypoints(), null);
             return "&" + url.substr('brouter?'.length + 1);
-        }, onHashChangeCb);
+        }, onHashChangeCb, onInvalidHashChangeCb);
         routingOptions.on('update', urlHash.updateHash, urlHash);
         nogos.on('update', urlHash.updateHash, urlHash);
         // waypoint add, move, delete (but last)
diff --git a/js/plugin/leaflet-fullHash.js b/js/plugin/leaflet-fullHash.js
index c3eb1a6..3ccd2de 100644
--- a/js/plugin/leaflet-fullHash.js
+++ b/js/plugin/leaflet-fullHash.js
@@ -5,10 +5,11 @@
             (doc_mode === undefined || doc_mode > 7);
     })();
 
-    L.Hash = function(map, layers, additionalCb, onHashChangeCb) {
+    L.Hash = function(map, layers, additionalCb, onHashChangeCb, onInvalidHashChangeCb) {
         this.onHashChange = L.Util.bind(this.onHashChange, this);
         this.additionalCb = additionalCb;
         this.onHashChangeCb = onHashChangeCb;
+        this.onInvalidHashChangeCb = onInvalidHashChangeCb;
         this.layers = layers;
         if (map) {
             this.init(map, layers);
@@ -127,6 +128,16 @@
                 return;
             }
             var parsed = this.parseHash(hash);
+            if (!parsed) {
+                // migration from old hash style to new one
+                if (this.onInvalidHashChangeCb != null) {
+                    var newHash = this.onInvalidHashChangeCb(hash);
+                    if (newHash != null && newHash != hash) {
+                        parsed = this.parseHash(newHash);
+                    }
+                }
+            }
+
             if (parsed) {
                 this.isUpdatingHash = true;