diff --git a/app/app.py b/app/app.py
index 911034b..f1d61b0 100644
--- a/app/app.py
+++ b/app/app.py
@@ -27,8 +27,11 @@ login_manager = LoginManager()
 login_manager.login_view = 'login'
 login_manager.init_app(app)
 
-if os.environ['SIGNUP_ENABLED'] == "YES":
-    signup_enabled = True
+if 'SIGNUP_ENABLED' in os.environ:
+    if os.environ['SIGNUP_ENABLED'] == "YES":
+        signup_enabled = True
+    else:
+        signup_enabled = False
 else:
     signup_enabled = False