diff --git a/kdc/digest.c b/kdc/digest.c
index 2f5316bf3..56c8cb84c 100644
--- a/kdc/digest.c
+++ b/kdc/digest.c
@@ -809,7 +809,7 @@ _kdc_do_digest(krb5_context context,
 		    ret = ENOMEM;
 		    goto out;
 		}
-		SHA1_Update(&ctx, clientNonce.data, clientNonce.length);
+		SHA1_Update(&ctx, clientNonce.data, ssize);
 		free(clientNonce.data);
 	    }
 	    SHA1_Update(&ctx, serverNonce.data, serverNonce.length);