diff --git a/.changeset/floppy-memes-warn.md b/.changeset/floppy-memes-warn.md
new file mode 100644
index 000000000000..60338e26d2d6
--- /dev/null
+++ b/.changeset/floppy-memes-warn.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-node': patch
+---
+
+fix: handling of PROTOCOL_HEADER and HOST_HEADER env vars
diff --git a/packages/adapter-node/src/handler.js b/packages/adapter-node/src/handler.js
index 47bf0c602b8d..299a97ed3b5a 100644
--- a/packages/adapter-node/src/handler.js
+++ b/packages/adapter-node/src/handler.js
@@ -182,8 +182,8 @@ function sequence(handlers) {
  * @returns
  */
 function get_origin(headers) {
-	const protocol = (protocol_header && headers[protocol_header]) ?? 'https';
-	const host = (host_header && headers[host_header]) ?? headers['host'];
+	const protocol = (protocol_header && headers[protocol_header]) || 'https';
+	const host = (host_header && headers[host_header]) || headers['host'];
 	const port = port_header && headers[port_header];
 
 	return port ? `${protocol}://${host}:${port}` : `${protocol}://${host}`;