diff --git a/types/node/v10/crypto.d.ts b/types/node/v10/crypto.d.ts
index 0d37716a7e..d9b89c8f29 100644
--- a/types/node/v10/crypto.d.ts
+++ b/types/node/v10/crypto.d.ts
@@ -258,8 +258,8 @@ declare module "crypto" {
 
     interface BasePrivateKeyEncodingOptions<T extends KeyFormat> {
         format: T;
-        cipher: string;
-        passphrase: string;
+        cipher?: string;
+        passphrase?: string;
     }
 
     interface RSAKeyPairOptions<PubF extends KeyFormat, PrivF extends KeyFormat> {