diff --git a/app/backend/lookuptool.py b/app/backend/lookuptool.py
index e8f530e03f..a3ee1d156b 100644
--- a/app/backend/lookuptool.py
+++ b/app/backend/lookuptool.py
@@ -16,5 +16,5 @@ def __init__(self, filename: Union[str, Path], key_field: str, name: str = "look
             for row in reader:
                 self.data[row[key_field]] =  "\n".join([f"{i}:{row[i]}" for i in row])
 
-    def lookup(self, key: str) -> Optional[str]:
+    def lookup(self, key: str) -> str:
         return self.data.get(key, "")