diff --git a/jest.config.js b/jest.config.js
index 4f4b694c..090703d2 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -5,7 +5,7 @@ module.exports = {
   globals: {
     'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV),
     'APP_BAR_TITLE': JSON.stringify(process.env.APP_BAR_TITLE || "Optuna Dashboard"),
-    'API_ENDPOINT': JSON.stringify(process.env.API_ENDPOINT),
+    'API_ENDPOINT': JSON.stringify(process.env.API_ENDPOINT || ""),
     'URL_PREFIX': JSON.stringify(process.env.URL_PREFIX || "/dashboard")
   }
 };
\ No newline at end of file