diff --git a/lib/check.js b/lib/check.js
index 8e77058..aae80d9 100644
--- a/lib/check.js
+++ b/lib/check.js
@@ -52,7 +52,7 @@
 		logging.message("check url %s for block mode %s", url, blockMode);
 		switch (url.protocol){
 			case "about:":
-				if (url.href === "about:blank"){
+				if (url.pathname === "blank"){
 					logging.message("use regular mode on about:blank");
 					break;
 				}
diff --git a/releaseNotes.txt b/releaseNotes.txt
index a39a213..75a10db 100644
--- a/releaseNotes.txt
+++ b/releaseNotes.txt
@@ -6,7 +6,7 @@ Version 1.10:
 		- 
 	
 	fixes:
-		- 
+		- always protect about:blank
 	
 	known issues:
 		- if a data URL is blocked the page action button does not appear
diff --git a/test/iframeAPI.js b/test/iframeAPI.js
index 5b6e9fe..f521891 100644
--- a/test/iframeAPI.js
+++ b/test/iframeAPI.js
@@ -86,9 +86,28 @@ const iframeAPI = function(){
 			}
 		},
 		{
-			name: "window.open",
+			name: "removed iframe",
 			prepare: async function openWindow(){
-				const newWindow = window.open("/");
+				const iframe = document.createElement("iframe");
+				document.body.appendChild(iframe);
+				const iframeWindow = iframe.contentWindow;
+				document.body.removeChild(iframe);
+				console.log("window of iframe directly after removing", iframeWindow);
+				return new Promise(function(resolve){
+					window.setTimeout(function(){
+						console.log("window of iframe in timeout", iframeWindow);
+						resolve(iframeWindow);
+					}, 1000);
+				});
+			}
+		},
+	];
+	
+	["/", "about:blank", "about:blank#"].forEach(function(url){
+		methods.push({
+			name: "window.open " + url,
+			prepare: async function openWindow(){
+				const newWindow = window.open(url);
 				if (newWindow){
 					return {
 						window: newWindow,
@@ -106,11 +125,12 @@ const iframeAPI = function(){
 					});
 				}
 			}
-		}
-	];
+		});
+	});
 	
 	function getPerformer(callback){
 		return async function perform(method){
+			console.log("run iframe method", method.name);
 			const api = await method.prepare();
 			callback(api.window, method.name);
 			api.cleanup();