diff --git a/src/app/shared/models/test.model.ts b/src/app/shared/models/test.model.ts
index cf084a6f3..719f05cd2 100644
--- a/src/app/shared/models/test.model.ts
+++ b/src/app/shared/models/test.model.ts
@@ -30,7 +30,7 @@ const Test = t.type({
   Owner: Option(t.string),
   Creation: t.string,
   GradingScaleId: Option(t.number),
-  GradingScale: t.string,
+  GradingScale: Option(t.string),
   Results: Option(t.array(Result)),
 });