diff --git a/util/mkdef.pl b/util/mkdef.pl
index efef49d64..13cf2aa19 100755
--- a/util/mkdef.pl
+++ b/util/mkdef.pl
@@ -101,7 +101,7 @@ my @known_algorithms = ( "RC2", "RC4", "RC5", "IDEA", "DES", "BF",
 			 # RFC3779
 			 "RFC3779",
 			 # TLS
-			 "TLSEXT", "PSK", "SRP",
+			 "TLSEXT", "PSK", "SRP", "HEARTBEATS",
 			 # CMS
 			 "CMS",
 			 # CryptoAPI Engine