diff --git a/db/schema.cds b/db/schema.cds
index 93a90df6..a470998e 100644
--- a/db/schema.cds
+++ b/db/schema.cds
@@ -20,7 +20,7 @@ entity Travel : managed {
   Progress       : Integer @readonly;
   Description    : String(1024);
   TravelStatus   : Association to TravelStatus @readonly;
-  to_Agency      : Association to TravelAgency;
+  to_Agency      : Association to TravelAgency @assert.target;
   to_Customer    : Association to Passenger;
   to_Booking     : Composition of many Booking on to_Booking.to_Travel = $self;
 };