diff --git a/types/bip39/index.d.ts b/types/bip39/index.d.ts
index a5d58cf961..6894ac3b30 100644
--- a/types/bip39/index.d.ts
+++ b/types/bip39/index.d.ts
@@ -17,7 +17,7 @@ export const wordlists: {
     spanish: string[];
 };
 
-export function entropyToMnemonic(entropyHex: string, wordlist?: string[]): string;
+export function entropyToMnemonic(entropyHex: Buffer | string, wordlist?: string[]): string;
 
 export function generateMnemonic(strength?: number, rng?: (size: number) => Buffer, wordlist?: string[]): string;