diff --git a/ngx_http_limit_traffic_rate_filter_module.c b/ngx_http_limit_traffic_rate_filter_module.c
index a96d015..37f7848 100644
--- a/ngx_http_limit_traffic_rate_filter_module.c
+++ b/ngx_http_limit_traffic_rate_filter_module.c
@@ -194,7 +194,7 @@ ngx_http_limit_traffic_rate_filter_handler(ngx_http_request_t *r)
                 lir->conn++;
                 ngx_http_limit_traffic_rate_filter_request_queue_t  *req;
                 req = ngx_slab_alloc_locked(shpool, sizeof(ngx_http_limit_traffic_rate_filter_request_queue_t));
-                if (node == NULL) {
+                if (req == NULL) {
                     ngx_shmtx_unlock(&shpool->mutex);
                     return NGX_HTTP_SERVICE_UNAVAILABLE;
                 }
@@ -530,6 +530,7 @@ ngx_http_limit_traffic_rate_filter_create_loc_conf(ngx_conf_t *cf)
         return NGX_CONF_ERROR;
     }
     conf->limit_traffic_rate = NGX_CONF_UNSET_SIZE;
+    conf->shm_zone= NGX_CONF_UNSET_PTR;
     return conf;
 }
 
@@ -540,6 +541,7 @@ ngx_http_limit_traffic_rate_filter_merge_loc_conf(ngx_conf_t *cf, void *parent,
     ngx_http_limit_traffic_rate_filter_conf_t *conf = child;
 
     ngx_conf_merge_size_value(conf->limit_traffic_rate, prev->limit_traffic_rate, 0);
+    ngx_conf_merge_ptr_value(conf->shm_zone, prev->shm_zone, NULL);
 
     return NGX_CONF_OK;
 }
@@ -772,10 +774,6 @@ ngx_http_limit_traffic_rate(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
     ngx_int_t   n;
     ngx_str_t  *value;
 
-    if (lircf->shm_zone) {
-        return "is duplicate";
-    }
-
     value = cf->args->elts;
 
     lircf->shm_zone = ngx_shared_memory_add(cf, &value[1], 0,