diff --git a/ospfd/ospf_packet.c b/ospfd/ospf_packet.c
index 44dca18..86fe4a2 100644
--- a/ospfd/ospf_packet.c
+++ b/ospfd/ospf_packet.c
@@ -1051,31 +1051,23 @@ #endif /* HAVE_OPAQUE_LSA */
 	}
     }
 
-  /* Master */
-  if (IS_SET_DD_MS (nbr->dd_flags))
-    {
-      nbr->dd_seqnum++;
-      /* Entire DD packet sent. */
-      if (!IS_SET_DD_M (dd->flags) && !IS_SET_DD_M (nbr->dd_flags))
-	OSPF_NSM_EVENT_SCHEDULE (nbr, NSM_ExchangeDone);
-      else
-	/* Send new DD packet. */
-	ospf_db_desc_send (nbr);
-    }
-  /* Slave */
+  /* Update DD Sequence number */
+  if (IS_SET_DD_MS (nbr->dd_flags)) /* Master */
+    nbr->dd_seqnum++;
+  else /* Slave */
+    nbr->dd_seqnum = ntohl (dd->dd_seqnum);
+
+  /* Any more DB-summaries to exchange? */
+  if (IS_SET_DD_M (dd->flags) || IS_SET_DD_M (nbr->dd_flags))
+    ospf_db_desc_send (nbr);
   else
     {
-      nbr->dd_seqnum = ntohl (dd->dd_seqnum);
-
-      /* When master's more flags is not set. */
-      if (!IS_SET_DD_M (dd->flags) && ospf_db_summary_isempty (nbr))
-	{
-	  nbr->dd_flags &= ~(OSPF_DD_FLAG_M);
-	  OSPF_NSM_EVENT_SCHEDULE (nbr, NSM_ExchangeDone);
-	}
-
-      /* Send DD packet in reply. */
-      ospf_db_desc_send (nbr);
+      /* Both sides have sent with More-bit clear: Exchange is done */
+      OSPF_NSM_EVENT_SCHEDULE (nbr, NSM_ExchangeDone);
+      
+      /* Slave must still send a DB-Desc, to acknowledge the masters packet */
+      if (!IS_SET_DD_MS (nbr->dd_flags))
+        ospf_db_desc_send (nbr);
     }
 
   /* Save received neighbor values from DD. */
@@ -1200,7 +1192,9 @@ #endif /* HAVE_OPAQUE_LSA */
 	      zlog_info ("Packet[DD]: Neighbor %s Negotiation done (Slave).",
 	      		 inet_ntoa(nbr->router_id));
 	      nbr->dd_seqnum = ntohl (dd->dd_seqnum);
-	      nbr->dd_flags &= ~(OSPF_DD_FLAG_MS|OSPF_DD_FLAG_I); /* Reset I/MS */
+	      
+	      /* Reset I/MS */
+	      UNSET_FLAG (nbr->dd_flags, (OSPF_DD_FLAG_MS|OSPF_DD_FLAG_I));
 	    }
 	  else
 	    {
@@ -1217,7 +1211,8 @@ #endif /* HAVE_OPAQUE_LSA */
 	{
 	  zlog_info ("Packet[DD]: Neighbor %s Negotiation done (Master).",
 		     inet_ntoa(nbr->router_id));
-	  nbr->dd_flags &= ~OSPF_DD_FLAG_I;
+          /* Reset I, leaving MS */
+          UNSET_FLAG (nbr->dd_flags, OSPF_DD_FLAG_I);
 	}
       else
 	{
@@ -2676,7 +2671,7 @@ #ifdef HAVE_OPAQUE_LSA
 #endif /* HAVE_OPAQUE_LSA */
   stream_putc (s, options);
 
-  /* Keep pointer to flags. */
+  /* DD flags */
   pp = stream_get_endp (s);
   stream_putc (s, nbr->dd_flags);
 
@@ -2685,12 +2680,21 @@ #endif /* HAVE_OPAQUE_LSA */
 
   if (ospf_db_summary_isempty (nbr))
     {
+      /* Sanity check:
+       *
+       * Must be here either:
+       * - Initial DBD (ospf_nsm.c)
+       *   - M must be set
+       * or
+       * - finishing Exchange, and DB-Summary list empty
+       *   - from ospf_db_desc_proc()
+       *   - M must not be set
+       */
       if (nbr->state >= NSM_Exchange)
-	{
-	  nbr->dd_flags &= ~OSPF_DD_FLAG_M;
-	  /* Set DD flags again */
-	  stream_putc_at (s, pp, nbr->dd_flags);
-	}
+	assert (!IS_SET_DD_M(nbr->dd_flags));
+      else
+        assert (IS_SET_DD_M(nbr->dd_flags));
+
       return length;
     }
 
@@ -2743,7 +2747,14 @@ #endif /* HAVE_OPAQUE_LSA */
 	    ospf_lsdb_delete (lsdb, lsa);
 	  }
     }
-
+  
+  /* Update 'More' bit */
+  if (ospf_db_summary_isempty (nbr))
+    {
+      UNSET_FLAG (nbr->dd_flags, OSPF_DD_FLAG_M);
+      /* Rewrite DD flags */
+      stream_putc_at (s, pp, nbr->dd_flags);
+    }
   return length;
 }