From f69c91abd383f6e61b17df94c1020943eefe0349 Mon Sep 17 00:00:00 2001
From: Andrew Stuart <andrew.stuart2@gmail.com>
Date: Fri, 28 Sep 2018 00:53:21 -0700
Subject: [PATCH] Fix nil pointer on watch function (#568)

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

diff --git a/viper.go b/viper.go
index f657b20..ce801a1 100644
--- a/viper.go
+++ b/viper.go
@@ -306,7 +306,9 @@ func (v *Viper) WatchConfig() {
 							if err != nil {
 								log.Println("error:", err)
 							}
-							v.onConfigChange(event)
+							if v.onConfigChange != nil {
+								v.onConfigChange(event)
+							}
 						}
 					}
 				case err := <-watcher.Errors: