diff --git a/backend/api/idfm_interface/idfm_types.py b/backend/api/idfm_interface/idfm_types.py
index c9530f4..5fef609 100644
--- a/backend/api/idfm_interface/idfm_types.py
+++ b/backend/api/idfm_interface/idfm_types.py
@@ -205,7 +205,7 @@ class Line(Struct):
 
 Lines = dict[str, Line]
 
-Destinations = dict[str, set[str]]
+Destinations = dict[int, set[str]]
 
 
 # TODO: Set structs frozen