diff --git a/src/Work/Formulas.ts b/src/Work/Formulas.ts
index 2ba890174..fe5305335 100644
--- a/src/Work/Formulas.ts
+++ b/src/Work/Formulas.ts
@@ -85,7 +85,7 @@ export function calculateFactionExp(person: IPerson, type: FactionWorkType): Wor
 export function calculateCost(classs: Class, location: Location): number {
   const serverMeta = serverMetadata.find((s) => s.specialName === location.name);
   const server = GetServer(serverMeta ? serverMeta.hostname : "");
-  const discount = (server as Server).backdoorInstalled ? 0.9 : 1;
+  const discount = (server as Server)?.backdoorInstalled ? 0.9 : 1;
   return classs.earnings.money * location.costMult * discount;
 }