diff --git a/src/angular-multi-select.js b/src/angular-multi-select.js
index 9149715..b800b49 100644
--- a/src/angular-multi-select.js
+++ b/src/angular-multi-select.js
@@ -319,10 +319,9 @@ angular_multi_select.directive('angularMultiSelect',
 
 						(function () {
 							var dupes = {};
+							var fnd = (function(d, o, n) { return fn(o, n, d); }).bind(this, dupes);
 							for(_idx in obj[key]) {
-								var new_obj = $scope._walk(obj[key][_idx], key, (function(d, o, n) {
-									return fn(o, n, d);
-								}).bind(this, dupes));
+								var new_obj = $scope._walk(obj[key][_idx], key, fnd);
 								if (new_obj !== null) {
 									sub.push(new_obj);
 								}
@@ -356,8 +355,9 @@ angular_multi_select.directive('angularMultiSelect',
 				});
 				$scope._walk(dst, attrs.groupProperty, function (o, e) {
 					var label = $scope._interpolatedItemLabel(o);
-					var prop = o[attrs.tickProperty];
-					o[attrs.tickProperty] = tree[e][label];
+					if (tree[e] && o[attrs.tickProperty] !== tree[e][label]) {
+					    o[attrs.tickProperty] = tree[e][label];
+					}
 					return true;
 				});
 			};
@@ -783,8 +783,8 @@ angular_multi_select.directive('angularMultiSelect',
 				if (typeof dupes === "undefined") return true;
 				var label = $scope._interpolatedItemLabel(obj);
 				if (dupes[label]) return false;
-				else return (dupes[label] = true)
-			}
+				else return (dupes[label] = true);
+			};
 
 			/**
 			 * Returns true if [attrs.searchProperty} matches the search input field (latinized, fuzzy match);