diff --git a/src/client/shared/requests/xmlhttprequest.ts b/src/client/shared/requests/xmlhttprequest.ts
index 52443f7..f548595 100644
--- a/src/client/shared/requests/xmlhttprequest.ts
+++ b/src/client/shared/requests/xmlhttprequest.ts
@@ -33,7 +33,7 @@ export default function (client: ScramjetClient, self: Self) {
 			if (!flagEnabled("syncxhr", client.url)) {
 				console.warn("ignoring request - sync xhr disabled in flags");
 
-				return;
+				return ctx.return(undefined);
 			}
 
 			// it's a sync request
diff --git a/src/controller/index.ts b/src/controller/index.ts
index 126b060..e988c96 100644
--- a/src/controller/index.ts
+++ b/src/controller/index.ts
@@ -7,7 +7,7 @@ export class ScramjetController {
 
 	constructor(config: Partial<ScramjetConfig>) {
 		// sane ish defaults
-		const defaultConfig: Partial<ScramjetConfig> = {
+		const defaultConfig: ScramjetConfig = {
 			prefix: "/scramjet/",
 			globals: {
 				wrapfn: "$scramjet$wrap",
@@ -26,7 +26,7 @@ export class ScramjetController {
 				client: "/scramjet.client.js",
 				sync: "/scramjet.sync.js",
 			},
-			defaultFlags: {
+			flags: {
 				serviceworkers: false,
 				naiiveRewriter: false,
 				captureErrors: true,
diff --git a/src/scramjet.ts b/src/scramjet.ts
index 031451a..810a2a2 100644
--- a/src/scramjet.ts
+++ b/src/scramjet.ts
@@ -27,7 +27,7 @@ export function loadCodecs() {
 }
 
 export function flagEnabled(flag: keyof ScramjetFlags, url: URL): boolean {
-	const value = $scramjet.config.defaultFlags[flag];
+	const value = $scramjet.config.flags[flag];
 	for (const regex in $scramjet.config.siteFlags) {
 		const partialflags = $scramjet.config.siteFlags[regex];
 		if (new RegExp(regex).test(url.href) && flag in partialflags) {
diff --git a/src/types.d.ts b/src/types.d.ts
index 121b7a9..888cf0b 100644
--- a/src/types.d.ts
+++ b/src/types.d.ts
@@ -54,7 +54,7 @@ interface ScramjetConfig {
 		client: string;
 		sync: string;
 	};
-	defaultFlags: ScramjetFlags;
+	flags: ScramjetFlags;
 	siteFlags: Record<string, Partial<ScramjetFlags>>;
 	codec: {
 		encode: string;
diff --git a/static/playground.js b/static/playground.js
index dc94718..9ebb5d3 100644
--- a/static/playground.js
+++ b/static/playground.js
@@ -6,10 +6,9 @@ const scramjet = new ScramjetController({
 		shared: "/scram/scramjet.shared.js",
 		sync: "/scram/scramjet.sync.js",
 	},
-	siteFlags: {
-		"https://worker-playground.glitch.me/.*": {
-			serviceworkers: true,
-		},
+	flags: {
+		serviceworkers: true,
+		syncxhr: true,
 	},
 });