diff --git a/README.md b/README.md
index ed78af25..9d1a9a3b 100644
--- a/README.md
+++ b/README.md
@@ -2161,7 +2161,8 @@ Returns a new `AxiosHeaders` instance.
 ### AxiosHeaders#toJSON(asStrings?)
 
 ```
-toJSON(asStrings?: boolean): RawAxiosHeaders;
+toJSON(asStrings: true): Record<string, string>;
+toJSON(asStrings?: false): Record<string, string | string[]>;
 ```
 
 Resolve all internal header values into a new null prototype object.
diff --git a/index.d.cts b/index.d.cts
index 30b093ef..2e17a8e4 100644
--- a/index.d.cts
+++ b/index.d.cts
@@ -66,7 +66,9 @@ declare class AxiosHeaders {
     ...targets: Array<AxiosHeaders | axios.RawAxiosHeaders | string | undefined | null>
   ): AxiosHeaders;
 
-  toJSON(asStrings?: boolean): axios.RawAxiosHeaders;
+  toJSON(asStrings: true): Record<string, string>;
+  toJSON(asStrings?: false): Record<string, string | string[]>;
+  toJSON(asStrings?: boolean): Record<string, string | string[]>;
 
   static from(thing?: AxiosHeaders | axios.RawAxiosHeaders | string): AxiosHeaders;
 
diff --git a/index.d.ts b/index.d.ts
index a43f3865..7304f5fa 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -47,7 +47,9 @@ export class AxiosHeaders {
     ...targets: Array<AxiosHeaders | RawAxiosHeaders | string | undefined | null>
   ): AxiosHeaders;
 
-  toJSON(asStrings?: boolean): RawAxiosHeaders;
+  toJSON(asStrings: true): Record<string, string>;
+  toJSON(asStrings?: false): Record<string, string | string[]>;
+  toJSON(asStrings?: boolean): Record<string, string | string[]>;
 
   static from(thing?: AxiosHeaders | RawAxiosHeaders | string): AxiosHeaders;