diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index 62f4f68d148..9769a9b1a7c 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -1592,8 +1592,8 @@ declare namespace ts {
     }
     interface ScriptReferenceHost {
         getCompilerOptions(): CompilerOptions;
-        getSourceFile(fileName: string): SourceFile;
-        getSourceFileByPath(path: Path): SourceFile;
+        getSourceFile(fileName: string): SourceFile | undefined;
+        getSourceFileByPath(path: Path): SourceFile | undefined;
         getCurrentDirectory(): string;
     }
     interface ParseConfigHost {
diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
index c7c8ba88d72..f185ef0daeb 100644
--- a/tests/baselines/reference/api/typescript.d.ts
+++ b/tests/baselines/reference/api/typescript.d.ts
@@ -1592,8 +1592,8 @@ declare namespace ts {
     }
     interface ScriptReferenceHost {
         getCompilerOptions(): CompilerOptions;
-        getSourceFile(fileName: string): SourceFile;
-        getSourceFileByPath(path: Path): SourceFile;
+        getSourceFile(fileName: string): SourceFile | undefined;
+        getSourceFileByPath(path: Path): SourceFile | undefined;
         getCurrentDirectory(): string;
     }
     interface ParseConfigHost {