diff --git a/lib/ansible/modules/crypto/openssl_certificate.py b/lib/ansible/modules/crypto/openssl_certificate.py
index 4e8d8250459..b42f6c227b2 100644
--- a/lib/ansible/modules/crypto/openssl_certificate.py
+++ b/lib/ansible/modules/crypto/openssl_certificate.py
@@ -127,9 +127,10 @@ options:
         description:
             - The certificate must be invalid at this point in time. The timestamp is formatted as an ASN.1 TIME.
 
-    notBefore:
+    not_before:
         description:
             - The certificate must start to become valid at this point in time. The timestamp is formatted as an ASN.1 TIME.
+        aliases: [ notBefore ]
 
     not_after:
         description: