diff --git a/configure.in b/configure.in
index da8bace74..8445d06ab 100644
--- a/configure.in
+++ b/configure.in
@@ -173,7 +173,7 @@ dnl
 dnl Header file checks
 dnl
 AC_STDC_HEADERS
-AC_HAVE_HEADERS(string.h strings.h unistd.h malloc.h paths.h)
+AC_HAVE_HEADERS(string.h strings.h unistd.h malloc.h paths.h sys/sockio.h)
 if test "$OS" != "ultrix" ; then
     AC_HAVE_HEADERS(termio.h termios.h)
 fi
@@ -201,6 +201,7 @@ dnl
 dnl library checks
 dnl
 AC_HAVE_LIBRARY(nsl)
+AC_HAVE_LIBRARY(socket)
 AC_HAVE_LIBRARY(ufc)
 dnl
 dnl OS-dependent libraries