diff --git a/lib/mess/tree/selector.js b/lib/mess/tree/selector.js
index 6d76477..6dfedaf 100644
--- a/lib/mess/tree/selector.js
+++ b/lib/mess/tree/selector.js
@@ -9,6 +9,13 @@ tree.Selector = function Selector(elements, filters, zoom, attachment, condition
     this.zoom = zoom;
     this.conditions = conditions;
     this.index = index;
+    this.updateID();
+};
+
+tree.Selector.prototype.updateID = function() {
+    var filters = Object.keys(this.filters);
+    filters.sort();
+    return this.id = (this.zoom & tree.Zoom.all) + '#' + filters.join('#');
 };
 
 tree.Selector.prototype.debug = function() {
@@ -26,12 +33,6 @@ tree.Selector.prototype.debug = function() {
     return str;
 };
 
-tree.Selector.prototype.hash = function() {
-    var filters = Object.keys(this.filters);
-    filters.sort();
-    return (this.zoom & tree.Zoom.all) + '[' + filters.join('][') + ']';
-};
-
 tree.Selector.prototype.sound = function() {
     if (!this.zoom) return false;
     return tree.Filter.sound(this.filters);
@@ -48,6 +49,7 @@ tree.Selector.prototype.clone = function() {
     obj.zoom = this.zoom;
     obj.conditions = this.conditions;
     obj.index = this.index;
+    obj.updateID();
     return obj;
 };
 
@@ -60,6 +62,7 @@ tree.Selector.prototype.merge = function(obj) {
     this.index = obj.index;
     this.zoom &= obj.zoom;
     this.conditions += obj.conditions;
+    this.updateID();
     return this;
 };
 
@@ -75,7 +78,7 @@ tree.Selector.prototype.mergeOrConditions = function(obj) {
         if (obj.zoom != tree.Zoom.all) {
             var clone = this.clone();
             clone.zoom &= obj.zoom;
-            if (clone.sound()) result[clone.hash()] = clone;
+            if (clone.sound()) result[clone.updateID()] = clone;
 
             var negatedZoom = ~obj.zoom;
             for (var id in obj.filters) {
@@ -84,7 +87,7 @@ tree.Selector.prototype.mergeOrConditions = function(obj) {
                 selector.zoom &= negatedZoom;
                 if (selector.sound()) {
                     tree.Filter.simplify(selector.filters);
-                    result[selector.hash()] = selector;
+                    result[selector.updateID()] = selector;
                 }
             }
         } else {
@@ -94,7 +97,8 @@ tree.Selector.prototype.mergeOrConditions = function(obj) {
                 selector.filters[id] = obj.filters[id];
                 if (selector.sound()) {
                     tree.Filter.simplify(selector.filters);
-                    result[selector.hash()] = selector;
+                    selector.updateID();
+                    result[selector.updateID()] = selector;
                 }
             }
         }
@@ -103,7 +107,8 @@ tree.Selector.prototype.mergeOrConditions = function(obj) {
         clone.zoom &= obj.zoom;
         if (clone.sound()) {
             tree.Filter.simplify(clone.filters);
-            result[clone.hash()] = clone;
+            clone.updateID();
+            result[clone.updateID()] = clone;
         }
     }
 
@@ -135,6 +140,7 @@ tree.Selector.prototype.negate = function() {
     obj.zoom = ~this.zoom;
     obj.conditions = this.conditions
     obj.index = this.index;
+    obj.updateID();
     return obj;
 };
 
diff --git a/test/specificity.test.js b/test/specificity.test.js
index 360f48b..1e13672 100644
--- a/test/specificity.test.js
+++ b/test/specificity.test.js
@@ -20,6 +20,7 @@ function cleanupItem(key, value) {
         else return tree.Zoom.toString(value);
     }
     else if (key === 'op') return value.value;
+    else if (key === 'id') return undefined;
     else if (key === 'val') return value.value;
     else if (key === 'conditions' && value == 0) return void null;
     else return value;