From 7ecfd216b14542e1bec159d58d5d7af992969bf8 Mon Sep 17 00:00:00 2001
From: Vinicius Schettino <schettino.viniciusjunqueira@gmail.com>
Date: Sat, 11 Jul 2020 15:54:46 -0300
Subject: [PATCH] Verify whether there is a Value before overriding

---
 flag_timestamp.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/flag_timestamp.go b/flag_timestamp.go
index 9fac1d1..0382a6b 100644
--- a/flag_timestamp.go
+++ b/flag_timestamp.go
@@ -118,7 +118,9 @@ func (f *TimestampFlag) Apply(set *flag.FlagSet) error {
 	if f.Layout == "" {
 		return fmt.Errorf("timestamp Layout is required")
 	}
-	f.Value = &Timestamp{}
+	if f.Value == nil {
+		f.Value = &Timestamp{}
+	}
 	f.Value.SetLayout(f.Layout)
 
 	if val, ok := flagFromEnvOrFile(f.EnvVars, f.FilePath); ok {