--- tcpdump.c.orig	2010-04-07 12:36:49.000000000 +0200
+++ tcpdump.c	2010-04-07 12:36:49.000000000 +0200
@@ -1191,6 +1191,10 @@
 			callback = dump_packet;
 			pcap_userdata = (u_char *)p;
 		}
+#ifdef HAVE_PCAP_DUMP_FLUSH
+		if (Uflag)
+			pcap_dump_flush(p);
+#endif
 	} else {
 		type = pcap_datalink(pd);
                 printinfo.ndo_type = 1;