diff --git a/doc/rawapi.txt b/doc/rawapi.txt
index 8213445e..3543bde1 100644
--- a/doc/rawapi.txt
+++ b/doc/rawapi.txt
@@ -383,7 +383,9 @@ Call these functions in the order of appearance:
     return ERR_OK;
   }
   
-  The input function pointer must point to the lwip ip_input().
+  For ethernet drivers, the input function pointer must point to the lwip
+  function ethernet_input() declared in "netif/etharp.h". Other drivers
+  must use ip_input() declared in "lwip/ip.h".
   
 - netif_set_default(struct netif *netif)
 
@@ -432,4 +434,4 @@ to match your application and network.
 
 For a production release it is recommended to set LWIP_STATS to 0.
 Note that speed performance isn't influenced much by simply setting
-high values to the memory options.
\ No newline at end of file
+high values to the memory options.