diff --git a/leaflet-core.html b/leaflet-core.html
index 1785909..0afcfaf 100644
--- a/leaflet-core.html
+++ b/leaflet-core.html
@@ -723,7 +723,8 @@
 		},
 
 		detached: function() {
-			this._mutationObserver.disconnect();
+			if(this._mutationObserver)
+				this._mutationObserver.disconnect();
 		},
 
 		_viewChanged: function(newValue, oldValue) {
diff --git a/leaflet-layer-group.html b/leaflet-layer-group.html
index 98d8b5f..5e343f8 100644
--- a/leaflet-layer-group.html
+++ b/leaflet-layer-group.html
@@ -17,7 +17,7 @@
 -->
 
 <dom-module id="leaflet-layer-group">
-	<template>
+	<template><content></content>
 	</template>
 </dom-module>
 
@@ -34,21 +34,22 @@
 			}	
 		},
 
-		ready: function() {
+		resetMutationObserver : function() {
 			this._mutationObserver = new MutationObserver(this.registerContainerOnChildren.bind(this));
 			this._mutationObserver.observe(this, {childList: true});
 		},
 	
 		_containerChanged: function() {
 			if (this.container) {
-				var feature = L.layerGroup()
+				var feature = L.layerGroup();
 				this.feature = feature;
 				this.feature.addTo(this.container);
-				this.registerContaierOnChildren();
+				this.registerContainerOnChildren();
 			}
 		},
 
-		registerContaierOnChildren: function() {
+		registerContainerOnChildren: function() {
+			this.resetMutationObserver();
 			for (var i = 0; i < this.children.length; i++) {
 				this.children[i].container = this.feature;
 			}