diff --git a/README b/README
index 8e0171d..efaa32c 100644
--- a/README
+++ b/README
@@ -9,7 +9,8 @@ that all these modules are played well together.
 
 The bundled software components are copyrighted by the respective copyright holders.
 
-To build ngx_openresty, follow the following steps
+To build ngx_openresty, you need a working perl (at least perl 5.6.x)
+in your PATH environment, and then follow the following steps:
 
 1. download the latest ngx_openresty tarball can be downloaded from