diff --git a/configure.in b/configure.in
index f3e0a5ed..cde9bc0c 100644
--- a/configure.in
+++ b/configure.in
@@ -81,6 +81,9 @@ AC_C_CONST
 dnl Check for types
 
 dnl Checks for library functions.
+AC_CHECK_FUNCS(nanosleep)
+AC_CHECK_FUNCS(sethostent endhostent)
+AC_CHECK_FUNCS(getnameinfo getaddrinfo inet_pton)
 
 dnl -- configure options --
 
diff --git a/src/net/sock.h b/src/net/sock.h
index 72a5a4bf..9b794079 100644
--- a/src/net/sock.h
+++ b/src/net/sock.h
@@ -22,6 +22,8 @@
 #ifndef __SOCK_H
 #define __SOCK_H
 
+#include <unistd.h>
+
 #ifdef _WIN32
 #include <winsock2.h>
 #endif