diff --git a/src/lib/server/LanguageService.ts b/src/lib/server/LanguageService.ts
index ef18f73..9c5a317 100644
--- a/src/lib/server/LanguageService.ts
+++ b/src/lib/server/LanguageService.ts
@@ -73,6 +73,10 @@ class LanguageService {
       url.searchParams.append('languages', lang)
     }
 
+    if (!env.TOLGEE_API_KEY) {
+      throw new Error('TOLGEE_API_KEY not set')
+    }
+
     const response = await fetch(url, {
       method: 'GET',
       headers: {