diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index 142dc3a9e7d..d9265b00e51 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -6791,6 +6791,7 @@ declare namespace ts.server.protocol {
         endLocation: Location;
         category: string;
         code: number;
+        source?: string;
         /** May store more in future. For now, this will simply be `true` to indicate when a diagnostic is an unused-identifier diagnostic. */
         reportsUnnecessary?: {};
         reportsDeprecated?: {};