diff --git a/reference/hwapi/reference.xml b/reference/hwapi/reference.xml
index 6b8fd8d9cf..5339521378 100644
--- a/reference/hwapi/reference.xml
+++ b/reference/hwapi/reference.xml
@@ -35,7 +35,8 @@
      Since 2001 there is a Hyperwave SDK available. It supports Java,
      JavaScript and C++. This PHP Extension is based on the C++ interface.
      In order to activate the hwapi support in PHP you will have to install
-     the Hyperwave SDK first.
+     the Hyperwave SDK first and configure PHP with
+     <option role="configure">--with-hwapi=&lt;dir$gt;</option>.
     </para>
    </section>