diff --git a/ssl/test/runner/conn.go b/ssl/test/runner/conn.go
index 21f491a..ec320ae 100644
--- a/ssl/test/runner/conn.go
+++ b/ssl/test/runner/conn.go
@@ -1383,7 +1383,7 @@
 	}
 
 	if !m.unmarshal(data) {
-		return nil, c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
+		return nil, c.in.setErrorLocked(c.sendAlert(alertDecodeError))
 	}
 	return m, nil
 }