diff --git a/qemu-os-win32.h b/qemu-os-win32.h
index 8eda4bdc20..b6533c0979 100644
--- a/qemu-os-win32.h
+++ b/qemu-os-win32.h
@@ -30,6 +30,32 @@
 #include <winsock2.h>
 #include "main-loop.h"
 
+/* Workaround for older versions of MinGW. */
+#ifndef ECONNREFUSED
+# define ECONNREFUSED WSAECONNREFUSED
+#endif
+#ifndef EINPROGRESS
+# define EINPROGRESS  WSAEINPROGRESS
+#endif
+#ifndef EHOSTUNREACH
+# define EHOSTUNREACH WSAEHOSTUNREACH
+#endif
+#ifndef EINTR
+# define EINTR        WSAEINTR
+#endif
+#ifndef EINPROGRESS
+# define EINPROGRESS  WSAEINPROGRESS
+#endif
+#ifndef ENETUNREACH
+# define ENETUNREACH  WSAENETUNREACH
+#endif
+#ifndef ENOTCONN
+# define ENOTCONN     WSAENOTCONN
+#endif
+#ifndef EWOULDBLOCK
+# define EWOULDBLOCK  WSAEWOULDBLOCK
+#endif
+
 /* Declaration of ffs() is missing in MinGW's strings.h. */
 int ffs(int i);
 
diff --git a/qemu_socket.h b/qemu_socket.h
index 51ad210a7f..a5d0a84fb6 100644
--- a/qemu_socket.h
+++ b/qemu_socket.h
@@ -8,12 +8,6 @@
 #include <ws2tcpip.h>
 
 #define socket_error() WSAGetLastError()
-#undef EWOULDBLOCK
-#undef EINTR
-#undef EINPROGRESS
-#define EWOULDBLOCK WSAEWOULDBLOCK
-#define EINTR       WSAEINTR
-#define EINPROGRESS WSAEINPROGRESS
 
 int inet_aton(const char *cp, struct in_addr *ia);
 
diff --git a/slirp/slirp.h b/slirp/slirp.h
index 46bfe4636d..f2c5eca892 100644
--- a/slirp/slirp.h
+++ b/slirp/slirp.h
@@ -15,18 +15,6 @@ typedef char *caddr_t;
 # include <sys/timeb.h>
 # include <iphlpapi.h>
 
-# undef EWOULDBLOCK
-# undef EINPROGRESS
-# undef ENOTCONN
-# undef EHOSTUNREACH
-# undef ENETUNREACH
-# undef ECONNREFUSED
-# define EWOULDBLOCK WSAEWOULDBLOCK
-# define EINPROGRESS WSAEINPROGRESS
-# define ENOTCONN WSAENOTCONN
-# define EHOSTUNREACH WSAEHOSTUNREACH
-# define ENETUNREACH WSAENETUNREACH
-# define ECONNREFUSED WSAECONNREFUSED
 #else
 # define ioctlsocket ioctl
 # define closesocket(s) close(s)