diff --git a/docs/tls/README.md b/docs/tls/README.md
index 7fe955f9e..b653ae13c 100644
--- a/docs/tls/README.md
+++ b/docs/tls/README.md
@@ -148,7 +148,7 @@ DNS.1 = localhost
 Run `openssl` by specifying the configuration file and enter a passphrase if prompted:
 
 ```sh
-openssl req -new -x509 -nodes -days 730 -key private.key -out public.crt -config openssl.conf
+openssl req -new -x509 -nodes -days 730 -keyout private.key -out public.crt -config openssl.conf
 ```
 
 ### <a name="using-gnu-tls"></a>3.3 Use GnuTLS (for Windows) to Generate a Certificate