diff --git a/src/reverse_proxy.rs b/src/reverse_proxy.rs
index 99a7c98..dc45869 100644
--- a/src/reverse_proxy.rs
+++ b/src/reverse_proxy.rs
@@ -52,8 +52,12 @@ fn copy_upgrade_headers(
 	old_headers: &HeaderMap<HeaderValue>,
 	new_headers: &mut HeaderMap<HeaderValue>,
 ) -> Result<()> {
+	// The Connection header is stripped as it is a hop header that we are not supposed to proxy.
+	// However, it might also contain an Upgrade directive, e.g. for Websockets:
+	// when that happen, we do want to preserve that directive.
 	if let Some(conn) = old_headers.get(header::CONNECTION) {
-		if conn.to_str()?.to_lowercase() == "upgrade" {
+		let conn_str = conn.to_str()?.to_lowercase();
+		if conn_str.split(',').map(str::trim).any(|x| x == "upgrade") {
 			if let Some(upgrade) = old_headers.get(header::UPGRADE) {
 				new_headers.insert(header::CONNECTION, "Upgrade".try_into()?);
 				new_headers.insert(header::UPGRADE, upgrade.clone());