diff --git a/plugins/out_splunk/splunk.c b/plugins/out_splunk/splunk.c
index c2531d7b240..bd89b35e06c 100644
--- a/plugins/out_splunk/splunk.c
+++ b/plugins/out_splunk/splunk.c
@@ -1072,7 +1072,7 @@ static struct flb_config_map config_map[] = {
     },
 
     {
-     FLB_CONFIG_MAP_STR, "http_passwd", "",
+     FLB_CONFIG_MAP_STR, "http_passwd", NULL,
      0, FLB_TRUE, offsetof(struct flb_splunk, http_passwd),
      "Set HTTP auth password"
     },