diff --git a/features/keychain/api/index.d.ts b/features/keychain/api/index.d.ts
index f2e0653..ede00d3 100644
--- a/features/keychain/api/index.d.ts
+++ b/features/keychain/api/index.d.ts
@@ -34,6 +34,7 @@ export interface KeychainApi {
   secp256k1: {
     signBuffer(params: { data: Buffer } & KeySource): Promise<Buffer>
     signBuffer(params: { data: Buffer; enc: 'der' } & KeySource): Promise<Buffer>
+    signSchnorr(params: { data: Buffer; extraEntropy?: Buffer } & KeySource): Promise<Buffer>
   }
 }