diff --git a/src/compiler/scanner.ts b/src/compiler/scanner.ts
index c8bb2ec0a25..5001ea58336 100644
--- a/src/compiler/scanner.ts
+++ b/src/compiler/scanner.ts
@@ -725,10 +725,14 @@ namespace ts {
         return accumulator;
     }
 
+    export function forEachLeadingCommentRange<U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean) => U): U | undefined;
+    export function forEachLeadingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T) => U, state: T): U | undefined;
     export function forEachLeadingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T) => U, state?: T): U | undefined {
         return iterateCommentRanges(/*reduce*/ false, text, pos, /*trailing*/ false, cb, state);
     }
 
+    export function forEachTrailingCommentRange<U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean) => U): U | undefined;
+    export function forEachTrailingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T) => U, state: T): U | undefined;
     export function forEachTrailingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T) => U, state?: T): U | undefined {
         return iterateCommentRanges(/*reduce*/ false, text, pos, /*trailing*/ true, cb, state);
     }
diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index bee3d4d2637..0a1385e9553 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -3254,8 +3254,10 @@ declare namespace ts {
     function isWhiteSpaceSingleLine(ch: number): boolean;
     function isLineBreak(ch: number): boolean;
     function couldStartTrivia(text: string, pos: number): boolean;
-    function forEachLeadingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T) => U, state?: T): U | undefined;
-    function forEachTrailingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T) => U, state?: T): U | undefined;
+    function forEachLeadingCommentRange<U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean) => U): U | undefined;
+    function forEachLeadingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T) => U, state: T): U | undefined;
+    function forEachTrailingCommentRange<U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean) => U): U | undefined;
+    function forEachTrailingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T) => U, state: T): U | undefined;
     function reduceEachLeadingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T, memo: U) => U, state: T, initial: U): U;
     function reduceEachTrailingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T, memo: U) => U, state: T, initial: U): U;
     function getLeadingCommentRanges(text: string, pos: number): CommentRange[] | undefined;
diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
index 09db501300b..82995f97bfa 100644
--- a/tests/baselines/reference/api/typescript.d.ts
+++ b/tests/baselines/reference/api/typescript.d.ts
@@ -2915,8 +2915,10 @@ declare namespace ts {
     function isWhiteSpaceSingleLine(ch: number): boolean;
     function isLineBreak(ch: number): boolean;
     function couldStartTrivia(text: string, pos: number): boolean;
-    function forEachLeadingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T) => U, state?: T): U | undefined;
-    function forEachTrailingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T) => U, state?: T): U | undefined;
+    function forEachLeadingCommentRange<U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean) => U): U | undefined;
+    function forEachLeadingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T) => U, state: T): U | undefined;
+    function forEachTrailingCommentRange<U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean) => U): U | undefined;
+    function forEachTrailingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T) => U, state: T): U | undefined;
     function reduceEachLeadingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T, memo: U) => U, state: T, initial: U): U;
     function reduceEachTrailingCommentRange<T, U>(text: string, pos: number, cb: (pos: number, end: number, kind: CommentKind, hasTrailingNewLine: boolean, state: T, memo: U) => U, state: T, initial: U): U;
     function getLeadingCommentRanges(text: string, pos: number): CommentRange[] | undefined;