diff --git a/index.bs b/index.bs
index 1ad3fe57e..ae25f6c96 100644
--- a/index.bs
+++ b/index.bs
@@ -5840,7 +5840,7 @@ The attestation certificate MUST have the following fields/extensions:
 
 - The Basic Constraints extension MUST have the CA component set to [FALSE].
 
-Additionally, Authority Information Access (AIA) extension with entry `id-ad-ocsp` and a CRL Distribution Point extension 
+Additionally, an Authority Information Access (AIA) extension with entry `id-ad-ocsp` and a CRL Distribution Point extension 
     [[RFC5280]] are both OPTIONAL as the status of many attestation certificates is available through authenticator metadata
     services. See, for example, the FIDO Metadata Service [[FIDOMetadataService]].