diff --git a/ospfd/ospf_packet.c b/ospfd/ospf_packet.c
index 5952d18..67926fc 100644
--- a/ospfd/ospf_packet.c
+++ b/ospfd/ospf_packet.c
@@ -351,7 +351,7 @@
   else
     {
       ck = getdata (OSPF_IF_PARAM (oi, auth_crypt)->tail);
-      auth_key = ck->auth_key;
+      auth_key = (char *) ck->auth_key;
     }
 
   /* Generate a digest for the entire packet + our secret key. */