diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index dfe2f613078..be11525ffb7 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -2888,7 +2888,7 @@ declare namespace ts {
         newLine: string;
         useCaseSensitiveFileNames: boolean;
         write(s: string): void;
-        writeOutputIsTty?(): boolean;
+        writeOutputIsTTY?(): boolean;
         readFile(path: string, encoding?: string): string | undefined;
         getFileSize?(path: string): number;
         writeFile(path: string, data: string, writeByteOrderMark?: boolean): void;
diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
index 6963bd95f72..c0cab668854 100644
--- a/tests/baselines/reference/api/typescript.d.ts
+++ b/tests/baselines/reference/api/typescript.d.ts
@@ -2888,7 +2888,7 @@ declare namespace ts {
         newLine: string;
         useCaseSensitiveFileNames: boolean;
         write(s: string): void;
-        writeOutputIsTty?(): boolean;
+        writeOutputIsTTY?(): boolean;
         readFile(path: string, encoding?: string): string | undefined;
         getFileSize?(path: string): number;
         writeFile(path: string, data: string, writeByteOrderMark?: boolean): void;