diff -ur a/lib/poll.c b/lib/poll.c
--- a/lib/poll.c
+++ b/lib/poll.c
@@ -23,6 +23,13 @@
 
 #include <config.h>
 
+/* Avoid namespace collision on Windows */
+#if defined _WIN32 && !defined __CYGWIN__
+# include <winsock2.h>
+# define pollfd pollfd_gnulib
+# define poll poll_gnulib
+#endif
+
 /* Specification.  */
 #include <poll.h>