diff --git a/src/core/ngx_conf_file.c b/src/core/ngx_conf_file.c
index 6084abb..f00cf01 100644
--- a/src/core/ngx_conf_file.c
+++ b/src/core/ngx_conf_file.c
@@ -934,7 +934,7 @@
 
     a = (ngx_array_t **) (p + cmd->offset);
 
-    if (*a == NULL) {
+    if (*a == NGX_CONF_UNSET_PTR) {
         *a = ngx_array_create(cf->pool, 4, sizeof(ngx_str_t));
         if (*a == NULL) {
             return NGX_CONF_ERROR;