diff --git a/index.d.cts b/index.d.cts
index 918e4821..916b9958 100644
--- a/index.d.cts
+++ b/index.d.cts
@@ -544,7 +544,7 @@ declare namespace axios {
           | LookupAddress
         >);
     withXSRFToken?: boolean | ((config: InternalAxiosRequestConfig) => boolean | undefined);
-    parseReviver?: (this: any, key: string, value: any, context?: { source: string }) => any;
+    parseReviver?: (this: any, key: string, value: any, context?: { source?: string }) => any;
     fetchOptions?:
       | Omit<RequestInit, 'body' | 'headers' | 'method' | 'signal'>
       | Record<string, any>;
diff --git a/index.d.ts b/index.d.ts
index fea8b7f4..e25555fa 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -441,7 +441,7 @@ export interface AxiosRequestConfig<D = any> {
         [address: LookupAddressEntry | LookupAddressEntry[], family?: AddressFamily] | LookupAddress
       >);
   withXSRFToken?: boolean | ((config: InternalAxiosRequestConfig) => boolean | undefined);
-  parseReviver?: (this: any, key: string, value: any, context?: { source: string }) => any;
+  parseReviver?: (this: any, key: string, value: any, context?: { source?: string }) => any;
   fetchOptions?: Omit<RequestInit, 'body' | 'headers' | 'method' | 'signal'> | Record<string, any>;
   httpVersion?: 1 | 2;
   http2Options?: Record<string, any> & {