diff --git a/viper.go b/viper.go
index 7027715..71bc631 100644
--- a/viper.go
+++ b/viper.go
@@ -457,6 +457,8 @@ func (v *Viper) getEnv(key string) (string, bool) {
 		key = v.envKeyReplacer.Replace(key)
 	}
 
+	key = strings.ReplaceAll(key, "-", "_")
+
 	val, ok := os.LookupEnv(key)
 
 	return val, ok && (v.allowEmptyEnv || val != "")