diff --git a/public/javascripts/core/collections/hash_table.js b/public/javascripts/core/collections/hash_table.js
index 13456d0..6c9b134 100644
--- a/public/javascripts/core/collections/hash_table.js
+++ b/public/javascripts/core/collections/hash_table.js
@@ -167,14 +167,14 @@ thisModule.addSlots(avocado.hashTable, function(add) {
   }, {category: ['accessing']});
 
   add.method('_each', function (iterator) {
-    for (var h in this._buckets) {
-      if (this._buckets.hasOwnProperty(h)) {
-        var b = this._buckets[h];
-        if (b instanceof Array) {
-          for (var i = 0, n = b.length; i < n; ++i) {
-            var entry = b[i];
-            iterator(entry);
-          }
+    var keys = Object.native_keys(this._buckets);
+    var length = keys.length;
+    for (var i = 0; i < length; i++) {
+      var b = this._buckets[keys[i]];
+      if(b && b instanceof Array) {
+        for (var j = 0, n = b.length; j < n; ++j) {
+          var entry = b[j];
+          iterator(entry);
         }
       }
     }
diff --git a/public/javascripts/core/deep_copy.js b/public/javascripts/core/deep_copy.js
index d4a31cb..9e77e01 100644
--- a/public/javascripts/core/deep_copy.js
+++ b/public/javascripts/core/deep_copy.js
@@ -42,20 +42,21 @@ thisModule.addSlots(avocado.deepCopier, function(add) {
         var isArray = isObj && (o instanceof Array);
         c = isObj ? (isArray ? [] : Object.create(o['__proto__'])) : eval("(" + o.toString() + ")");
         var thisCopier = this;
-        for (var n in o) {
-          if (o.hasOwnProperty(n)) {
-            var contents = o[n];
-            if (n === '__annotation__') {
-              c[n] = contents.copy();
+        var keys = Object.native_keys(o);
+        var length = keys.length;
+        for (var j = 0; j < length; ++j){
+          var n = keys[j];
+          var contents = o[n];
+          if (n === '__annotation__') {
+            c[n] = contents.copy();
+          } else if (contents) {
+            var contentsType = typeof(contents);
+            var contentsCreatorSlot = (contentsType === 'object' || contentsType === 'function') && avocado.annotator.theCreatorSlotOf(contents);
+            if (contentsCreatorSlot && contentsCreatorSlot.name === n && contentsCreatorSlot.holder === o) {
+              c[n] = thisCopier.createCopyOf(contents);
+              avocado.annotator.annotationOf(c[n]).setCreatorSlot(n, c);
             } else {
-              var contentsType = typeof(contents);
-              var contentsCreatorSlot = (contentsType === 'object' || contentsType === 'function') && avocado.annotator.theCreatorSlotOf(contents);
-              if (contentsCreatorSlot && contentsCreatorSlot.name === n && contentsCreatorSlot.holder === o) {
-                c[n] = thisCopier.createCopyOf(contents);
-                avocado.annotator.annotationOf(c[n]).setCreatorSlot(n, c);
-              } else {
-                c[n] = contents;
-              }
+              c[n] = contents;
             }
           }
         }
@@ -87,12 +88,15 @@ thisModule.addSlots(avocado.deepCopier, function(add) {
       var thisCopier = this;
       var originalsAndCopies = this._originalsAndCopies;
       var originalsAndCopiesCount = originalsAndCopies.length;
-      for (var n in c) {
-        if (c.hasOwnProperty(n)) {
+      var keys = Object.native_keys(c);
+      var length = keys.length;
+      for (var j = 0; j < length; ++j){
+        var n = keys[j];
+        var contents = c[n];
+        if (contents) {
           if (n === '__annotation__') {
             // just ignore it, no refs to fix up, I think - oh, actually, could do the creator slot, but we've already done it up above
-          } else {
-            var contents = c[n];
+          } else {            
             var contentsType = typeof(contents);
             if (contentsType === 'object' || contentsType === 'function') {
               var wasInternalRef = false;
diff --git a/public/javascripts/lk/Base.js b/public/javascripts/lk/Base.js
index 5964d25..d2c0199 100644
--- a/public/javascripts/lk/Base.js
+++ b/public/javascripts/lk/Base.js
@@ -47,7 +47,8 @@ Object.defineProperties = function(object, descriptorSet) {
 	}
 	return object;
 }
-	 
+
+Object.native_keys = Object.keys;	 
 Object.defineProperties(Object, {
   // I like mine better. -- Adam
   /*
@@ -62,12 +63,15 @@ Object.defineProperties(Object, {
 	*/
 
 	keys: { 
-		value: function(object, optFast) {
-			if (typeof object !== 'object') throw new TypeError('not an object');
-			var names = []; // check behavior wrt arrays
-			for (var name in object) {
-				if (object.hasOwnProperty(name)) 
-					names.push(name);
+	        value: function(object, optFast) {
+                        if (typeof object !== 'object' && typeof object !== 'function') throw new TypeError('not an object');
+                        var names = []; // check behavior wrt arrays
+                        var keys = Object.native_keys(object);
+                        var length = keys.length;
+		        for (var i = 0; i < length; ++i) {
+                                var name = keys[i];
+                                if (object[name])
+                                        names.push(name);
 			}
 			if (!optFast) names.sort();
 			return names;