diff --git a/libusb/libusb.h b/libusb/libusb.h
index de2d050..beff229 100644
--- a/libusb/libusb.h
+++ b/libusb/libusb.h
@@ -833,6 +833,10 @@ typedef void (LIBUSB_CALL *libusb_transfer_cb_fn)(struct libusb_transfer *transf
  * completed, the library populates the transfer with the results and passes
  * it back to the user.
  */
+#if defined(OS_WIN)
+#pragma warning(push)
+#pragma warning(disable:4200)
+#endif  // defined(OS_WIN)
 struct libusb_transfer {
 	/** Handle of the device that this transfer will be submitted to */
 	libusb_device_handle *dev_handle;
@@ -884,12 +888,15 @@ struct libusb_transfer {
 	/** Isochronous packet descriptors, for isochronous transfers only. */
 	struct libusb_iso_packet_descriptor iso_packet_desc
 #if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
-	[] /* valid C99 code */
+       [] /* valid C99 code */
 #else
-	[0] /* non-standard, but usually working code */
+       [0] /* non-standard, but usually working code */
 #endif
-	;
+       ;
 };
+#if defined(OS_WIN)
+#pragma warning(pop)
+#endif  // defined(OS_WIN)
 
 /** \ingroup misc
  * Capabilities supported by this instance of libusb. Test if the running
diff --git a/libusb/os/poll_windows.h b/libusb/os/poll_windows.h
index fee89f5..76bab0f 100644
--- a/libusb/os/poll_windows.h
+++ b/libusb/os/poll_windows.h
@@ -19,6 +19,9 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  *
  */
+
+#ifndef LIBUSB_POLL_WINDOWS_H
+#define LIBUSB_POLL_WINDOWS_H
 #pragma once
 
 #if defined(_MSC_VER)
@@ -50,19 +53,6 @@ extern enum windows_version windows_version;
 
 #define MAX_FDS     256
 
-#define POLLIN      0x0001    /* There is data to read */
-#define POLLPRI     0x0002    /* There is urgent data to read */
-#define POLLOUT     0x0004    /* Writing now will not block */
-#define POLLERR     0x0008    /* Error condition */
-#define POLLHUP     0x0010    /* Hung up */
-#define POLLNVAL    0x0020    /* Invalid request: fd not open */
-
-struct pollfd {
-    int fd;           /* file descriptor */
-    short events;     /* requested events */
-    short revents;    /* returned events */
-};
-
 // access modes
 enum rw_type {
 	RW_NONE,
@@ -118,3 +108,4 @@ do {                                                    \
 } while (0)
 #endif
 
+#endif /* LIBUSB_POLL_WINDOWS_H */
diff --git a/libusb/os/windows_usb.h b/libusb/os/windows_usb.h
index b629d18..6dbfaf5 100644
--- a/libusb/os/windows_usb.h
+++ b/libusb/os/windows_usb.h
@@ -101,8 +101,6 @@ const GUID GUID_DEVINTERFACE_USB_DEVICE = { 0xA5DCBF10, 0x6530, 0x11D2, {0x90, 0
 #if !defined(GUID_DEVINTERFACE_USB_HUB)
 const GUID GUID_DEVINTERFACE_USB_HUB = { 0xF18A0E88, 0xC30C, 0x11D0, {0x88, 0x15, 0x00, 0xA0, 0xC9, 0x06, 0xBE, 0xD8} };
 #endif
-const GUID GUID_NULL = { 0x00000000, 0x0000, 0x0000, {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00} };
-
 
 /*
  * Multiple USB API backend support
diff --git a/msvc/config.h b/msvc/config.h
index 43b4d4e..9ac6134 100644
--- a/msvc/config.h
+++ b/msvc/config.h
@@ -19,3 +19,5 @@
 
 /* type of second poll() argument */
 #define POLL_NFDS_TYPE unsigned int
+
+#include <Winsock2.h>