diff --git a/ares/config-win32.h b/ares/config-win32.h
index f9df53295..5026728b4 100644
--- a/ares/config-win32.h
+++ b/ares/config-win32.h
@@ -30,5 +30,6 @@
 #define HAVE_STRUCT_IN6_ADDR
 #define HAVE_STRUCT_SOCKADDR_IN6
 #define HAVE_STRUCT_ADDRINFO
+#define HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID
 
 #endif  /* __CONFIG_WIN32_H */