diff --git a/web/b3desk/__init__.py b/web/b3desk/__init__.py
index 69a5664f..92651155 100755
--- a/web/b3desk/__init__.py
+++ b/web/b3desk/__init__.py
@@ -21,6 +21,7 @@
 from flask_migrate import Migrate
 from flask_wtf.csrf import CSRFError
 from flask_wtf.csrf import CSRFProtect
+from jinja2 import StrictUndefined
 
 
 CRITICAL_VARS = ["OIDC_ISSUER", "OIDC_CLIENT_SECRET", "BIGBLUEBUTTON_SECRET"]
@@ -88,6 +89,9 @@ def setup_jinja(app):
     from b3desk.session import has_user_session
     from b3desk.session import get_current_user
 
+    if app.debug or app.testing:
+        app.jinja_env.undefined = StrictUndefined
+
     @app.context_processor
     def global_processor():
         if has_user_session():