diff --git a/doc/quickstart.md b/doc/quickstart.md
index eb974692..b7e3afb2 100644
--- a/doc/quickstart.md
+++ b/doc/quickstart.md
@@ -46,13 +46,8 @@ server {
   RewriteRule /(.*)           http://localhost:8080/$1 [P,L]
 
   ProxyRequests off
-
-  RequestHeader set X-Forwarded-Proto https
-  RequestHeader set X-Forwarded-Port 443
-
-  ProxyPass / http://localhost:8080/ nocanon
+  ProxyPass        / http://localhost:8080/ nocanon
   ProxyPassReverse / http://localhost:8080/
-
 </VirtualHost>
 ```
 
diff --git a/src/server.ts b/src/server.ts
index 1fd57b9f..4312d36d 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -331,7 +331,7 @@ export abstract class Server {
 		this.ensureGet(request);
 		if (!this.authenticate(request)) {
 			throw new HttpError("Unauthorized", HttpCode.Unauthorized);
-		} else if (request.headers.upgrade !== "websocket") {
+		} else if (!request.headers.upgrade || request.headers.upgrade.toLowerCase() !== "websocket") {
 			throw new Error("HTTP/1.1 400 Bad Request");
 		}