diff --git a/doc/bird.sgml b/doc/bird.sgml
index c7d8b792..220ac94a 100644
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -1370,7 +1370,7 @@ protocol ospf <name> {
 			rx buffer [normal|large|<num>];
 			type [broadcast|nonbroadcast|pointopoint];
 			strict nonbroadcast <switch>;
-			authentication [none|simple|cryptographics];
+			authentication [none|simple|cryptographic];
 			password "<text>";
 			password "<text>" {
 				id <num>;
@@ -1390,7 +1390,7 @@ protocol ospf <name> {
 			wait <num>;
 			dead count <num>;
 			dead <num>;
-			authentication [none|simple|cryptographics];
+			authentication [none|simple|cryptographic];
 			password "<text>";
 		};
 	};