diff --git a/docs/users_guide/ffi-chap.xml b/docs/users_guide/ffi-chap.xml
index e7d5a0c37d833edd8a1f3a55434ebc900fbf5f06..ab099b2953e9e6aef18837a69f9c1b94bd246fa5 100644
--- a/docs/users_guide/ffi-chap.xml
+++ b/docs/users_guide/ffi-chap.xml
@@ -110,7 +110,7 @@ OK:
 
 <programlisting>
 foreign import ccall interruptible
-   "sleep" :: CUint -> IO CUint
+   "sleep" sleepBlock :: CUint -> IO CUint
 </programlisting>
 
           <literal>interruptible</literal> behaves exactly as