diff --git a/messaging.js b/messaging.js
index 1e7cc94e..0d356256 100644
--- a/messaging.js
+++ b/messaging.js
@@ -1,12 +1,15 @@
 // keep message channel open for sendResponse in chrome.runtime.onMessage listener
 const KEEP_CHANNEL_OPEN = true;
+const OWN_ORIGIN = chrome.runtime.getURL('');
 
 function notifyAllTabs(request) {
-	chrome.windows.getAll({populate: true}, function(windows) {
-		windows.forEach(function(win) {
-			win.tabs.forEach(function(tab) {
-				chrome.tabs.sendMessage(tab.id, request);
-				updateIcon(tab);
+	chrome.windows.getAll({populate: true}, windows => {
+		windows.forEach(win => {
+			win.tabs.forEach(tab => {
+				if (request.codeIsUpdated !== false || tab.url.startsWith(OWN_ORIGIN)) {
+					chrome.tabs.sendMessage(tab.id, request);
+					updateIcon(tab);
+				}
 			});
 		});
 	});
diff --git a/storage.js b/storage.js
index 1a0a1fce..776c71d3 100644
--- a/storage.js
+++ b/storage.js
@@ -105,11 +105,13 @@ function saveStyle(style, {notify = true} = {}) {
 			if (style.id) {
 				style.id = Number(style.id);
 				os.get(style.id).onsuccess = eventGet => {
-					style = Object.assign({}, eventGet.target.result, style);
+					const oldStyle = Object.assign({}, eventGet.target.result);
+					const codeIsUpdated = !styleSectionsEqual(style, oldStyle);
+					style = Object.assign(oldStyle, style);
 					os.put(style).onsuccess = eventPut => {
 						style.id = style.id || eventPut.target.result;
 						if (notify) {
-							notifyAllTabs({method: 'styleUpdated', style});
+							notifyAllTabs({method: 'styleUpdated', style, codeIsUpdated});
 						}
 						invalidateCache(notify);
 						resolve(style);
@@ -576,6 +578,9 @@ function getSync() {
 }
 
 function styleSectionsEqual(styleA, styleB) {
+	if (!styleA.sections || !styleB.sections) {
+		return undefined;
+	}
 	if (styleA.sections.length != styleB.sections.length) {
 		return false;
 	}