diff --git a/canvasblocker.xpi b/canvasblocker.xpi
index df302b6..cb1241b 100644
Binary files a/canvasblocker.xpi and b/canvasblocker.xpi differ
diff --git a/data/inject.js b/data/inject.js
index 96614c2..c3a774e 100644
--- a/data/inject.js
+++ b/data/inject.js
@@ -241,49 +241,27 @@
 	
 	// Communication with main.js
 	
-	function checkAbout(){
-		return document.location.protocol === "about:";
-	}
-	
-	function checkPDF(blocking){
-		if (document.contentType.match(/\/pdf$/i)){
-			self.port.emit("isPDF", blocking);
-			return true;
-		}
-		return false;
-	}
-	
-	self.port.on("block", function(force){
-		if (force || !checkAbout() || !checkPDF("block")){
-			blockMode.getContext.status = "block";
-			blockMode.readAPI.status = "allow";
-		}
+	self.port.on("block", function(){
+		blockMode.getContext.status = "block";
+		blockMode.readAPI.status = "allow";
 	});
-	self.port.on("ask", function(force, askOnce){
-		if (force || !checkAbout() || !checkPDF("askVisible")){
-			blockMode.getContext.status = "ask";
-			blockMode.getContext.askStatus.askOnce = askOnce;
-			blockMode.readAPI.status = "allow";
-		}
+	self.port.on("ask", function(askOnce){
+		blockMode.getContext.status = "ask";
+		blockMode.getContext.askStatus.askOnce = askOnce;
+		blockMode.readAPI.status = "allow";
 	});
-	self.port.on("blockReadout", function(force){
-		if (force || !checkAbout() || !checkPDF("blockReadout")){
-			blockMode.getContext.status = "allow";
-			blockMode.readAPI.status = "block";
-		}
+	self.port.on("blockReadout", function(){
+		blockMode.getContext.status = "allow";
+		blockMode.readAPI.status = "block";
 	});
-	self.port.on("fakeReadout", function(force){
-		if (force || !checkAbout() || !checkPDF("fakeReadout")){
-			blockMode.getContext.status = "allow";
-			blockMode.readAPI.status = "fake";
-		}
+	self.port.on("fakeReadout", function(){
+		blockMode.getContext.status = "allow";
+		blockMode.readAPI.status = "fake";
 	});
-	self.port.on("askReadout", function(force, askOnce){
-		if (force || !checkAbout() || !checkPDF("askReadout")){
-			blockMode.getContext.status = "allow";
-			blockMode.readAPI.status = "ask";
-			blockMode.readAPI.askStatus.askOnce = askOnce;
-		}
+	self.port.on("askReadout", function(askOnce){
+		blockMode.getContext.status = "allow";
+		blockMode.readAPI.status = "ask";
+		blockMode.readAPI.askStatus.askOnce = askOnce;
 	});
 	self.port.on("unblock", function(){
 		blockMode.getContext.status = "allow";
diff --git a/lib/main.js b/lib/main.js
index 96af2bf..ae40097 100644
--- a/lib/main.js
+++ b/lib/main.js
@@ -87,7 +87,6 @@
 	});
 	
 	function checkURL(url){
-		url = new URL(url);
 		var mode = "block";
 		switch (prefs.blockMode){
 			case "blockEverything":
@@ -133,8 +132,18 @@
 	}
 	function checkWorker(worker){
 		try {
-			var mode = checkURL(worker.url);
-			worker.port.emit(mode, false, prefs.askOnlyOnce);
+			var mode;
+			var url = new URL(worker.url)
+			if (
+				(url.protocol === "about:") ||
+				(prefs.allowPDFCanvas && worker.tab.contentType.match(/\/pdf$/i))
+			){
+				mode = "unblock";
+			}
+			else {
+				var mode = checkURL(url);
+			}
+			worker.port.emit(mode, prefs.askOnlyOnce);
 		}
 		catch (e){
 			console.log("Error updating " + worker.url + ": " + e.message);
@@ -158,14 +167,6 @@
 			worker.on("detach", function(){
 				array.remove(workers, this);
 			});
-			worker.port.on("isPDF", function(blocking){
-				if (prefs.allowPDFCanvas){
-					this.emit("unblock");
-				}
-				else {
-					this.emit(blocking, true, prefs.askOnlyOnce);
-				}
-			});
 			["", "Readout"].forEach(function(type){
 				["", "Visible", "Invisible"].forEach(function(visibility){
 						var text = "askFor" + visibility + type + "Permission";