--- async/cpp/AsyncCppDnsLookupWorker.cpp.old	2012-07-31 17:45:31.000000000 +0000
+++ async/cpp/AsyncCppDnsLookupWorker.cpp	2012-07-31 17:45:24.000000000 +0000
@@ -38,6 +38,7 @@
  *
  ****************************************************************************/
 
+#include <unistd.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>