diff --git a/lib/krb5/crypto-arcfour.c b/lib/krb5/crypto-arcfour.c
index 0a5131665..e16b70cca 100644
--- a/lib/krb5/crypto-arcfour.c
+++ b/lib/krb5/crypto-arcfour.c
@@ -317,7 +317,7 @@ struct _krb5_encryption_type _krb5_enctype_arcfour_hmac_md5 = {
     8,
     &keytype_arcfour,
     &_krb5_checksum_hmac_md5,
-    NULL,
+    &_krb5_checksum_hmac_md5,
     F_SPECIAL,
     ARCFOUR_encrypt,
     0,