diff --git a/package.json b/package.json
index 1361144..a0788aa 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@mierune/sveltekit-firebase-auth-ssr",
-	"version": "0.0.15",
+	"version": "0.0.16",
 	"scripts": {
 		"dev": "vite dev",
 		"build": "vite build && npm run package",
diff --git a/src/lib/firebase-auth/server.ts b/src/lib/firebase-auth/server.ts
index ab502f6..a34908f 100644
--- a/src/lib/firebase-auth/server.ts
+++ b/src/lib/firebase-auth/server.ts
@@ -37,6 +37,10 @@ export function createAuthHandle({
 	keyStore: keyStoreMaker
 }: AuthHandleOptions): Handle {
 	return async ({ event, resolve }) => {
+		if (!serviceAccountCredential && !emulatorEnv.FIREBASE_AUTH_EMULATOR_HOST) {
+			console.error('FIREBASE_SERVICE_ACCOUNT_KEY is not set. Authentication will not work.');
+		}
+
 		const auth = getAuth(projectId, keyStoreMaker(event.platform), serviceAccountCredential);
 		const { request, cookies, fetch } = event;