diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
index 4a957d2..5683c24 100644
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -2659,6 +2659,17 @@
 
     value = cf->args->elts;
 
+    if (ngx_strstr(value[1].data, "$document_root") != 0
+        || ngx_strstr(value[1].data, "${document_root}") != 0)
+    {
+        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                           "the $document_root variable may not be used "
+                           "in the \"%V\" directive",
+                           &cmd->name);
+
+        return NGX_CONF_ERROR;
+    }
+
     lcf->alias = alias;
     lcf->root = value[1];