diff --git a/src/crypto_key.d.ts b/src/crypto_key.d.ts
index 48efef298..9aa81a687 100644
--- a/src/crypto_key.d.ts
+++ b/src/crypto_key.d.ts
@@ -1,2 +1,2 @@
-export function extractPublic(keypair: String): String;
-export function generate(): String;
+export function extractPublic(keypair: string): string;
+export function generate(): string;