diff --git a/src/win32.h b/src/win32.h
index 277d9292..4ffcb7c5 100644
--- a/src/win32.h
+++ b/src/win32.h
@@ -44,6 +44,23 @@
 #undef ERROR
 #endif
 
+#ifndef AI_ALL
+#define AI_ALL 0x00000100
+#endif
+
+#ifndef AI_ADDRCONFIG
+#define AI_ADDRCONFIG 0x00000400
+#endif
+
+#ifndef AI_V4MAPPED
+#define AI_V4MAPPED 0x00000800
+#endif
+
+#ifndef IPV6_V6ONLY
+#define IPV6_V6ONLY 27 // Treat wildcard bind as AF_INET6-only.
+#endif
+
+
 #define EWOULDBLOCK WSAEWOULDBLOCK
 #define errno WSAGetLastError()
 #define close(fd) closesocket(fd)