@@ -595,10 +595,13 @@
 	AC_DEFINE(OF_HAVE_LINK, 1, [Whether we have link()])
 ])
 AC_CHECK_FUNC(symlink, [
 	AC_DEFINE(OF_HAVE_SYMLINK, 1, [Whether we have symlink()])
 ])
+AC_CHECK_FUNC(pipe, [
+	AC_DEFINE(OF_HAVE_PIPE, 1, [Whether we have pipe()])
+])
 
 AC_ARG_ENABLE(sockets,
 	AS_HELP_STRING([--disable-sockets], [disable socket support]))
 AS_IF([test x"$enable_sockets" != x"no"], [
 	AC_DEFINE(OF_HAVE_SOCKETS, 1, [Whether we have sockets])
@@ -606,10 +609,16 @@
 
 	AC_CHECK_LIB(socket, socket, LIBS="$LIBS -lsocket")
 	AC_CHECK_LIB(network, socket, LIBS="$LIBS -lnetwork")
 	AC_CHECK_LIB(ws2_32, main, LIBS="$LIBS -lws2_32")
 
+	AC_CHECK_HEADER(sys/socket.h, [
+		AC_DEFINE(OF_HAVE_SYS_SOCKET_H, 1,
+			[Whether we have sys/socket.h])
+	])
+	AC_CHECK_HEADERS([netinet/in.h arpa/inet.h netdb.h])
+
 	AC_CHECK_FUNC(kqueue, [
 		AC_DEFINE(HAVE_KQUEUE, 1, [Whether we have kqueue])
 		AC_SUBST(OFSTREAMOBSERVER_KQUEUE_M, "OFStreamObserver_kqueue.m")
 	])
 	AC_CHECK_HEADER(poll.h, [
@@ -618,10 +627,11 @@
 	])
 	AC_CHECK_HEADER(sys/select.h, [
 		AC_DEFINE(HAVE_SYS_SELECT_H, 1, [Whether we have sys/select.h])
 		AC_SUBST(OFSTREAMOBSERVER_SELECT_M, "OFStreamObserver_select.m")
 	])
+
 	case "$host_os" in
 		mingw*)
 			AC_SUBST(OFSTREAMOBSERVER_SELECT_M,
 				"OFStreamObserver_select.m")
 			;;
@@ -699,16 +709,19 @@
 			])
 
 			AS_IF([test x"$have_threadsafe_getaddrinfo" = x"yes"], [
 				AC_DEFINE(HAVE_THREADSAFE_GETADDRINFO, 1,
 					[Whether getaddrinfo is thread-safe])
+			], [
+				AC_CHECK_FUNCS([h_errno hstrerror])
 			])
 
 			AC_MSG_RESULT($have_threadsafe_getaddrinfo)
 		])
 	], [
 		AC_MSG_RESULT(no)
+		AC_CHECK_FUNCS([h_errno hstrerror])
 	])
 ])
 
 AS_IF([test x"$enable_sockets" != x"no" -a x"$enable_threads" != x"no"], [
 	AC_SUBST(OFHTTPCLIENTTESTS_M, "OFHTTPClientTests.m")
@@ -717,11 +730,11 @@
 case "$host" in
 	*-*-mingw*)
 		have_processes="yes"
 		;;
 	*)
-		AC_CHECK_FUNCS([fork pipe dup2 execvp kill], [
+		AC_CHECK_FUNCS([fork dup2 execvp kill], [
 			if test x"$ac_cv_func_fork" = x"yes" \
 			    -a x"$ac_cv_func_pipe" = x"yes" \
 			    -a x"$ac_cv_func_dup2" = x"yes" \
 			    -a x"$ac_cv_func_execvp" = x"yes" \
 			    -a x"$ac_cv_func_kill" = x"yes"; then