diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8553b636..ba97eca4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -483,6 +483,7 @@ endif()
 if (MINGW)
 	set(LWS_MINGW_SUPPORT 1)
 	set(CMAKE_C_FLAGS "-D__USE_MINGW_ANSI_STDIO ${CMAKE_C_FLAGS}")
+	add_definitions(-DWINVER=0x0601 -D_WIN32_WINNT=0x0601)
 endif()
 
 if (LWS_SSL_SERVER_WITH_ECDH_CERT)
diff --git a/lib/libwebsockets.c b/lib/libwebsockets.c
index 1b980dc1..ea555ab7 100644
--- a/lib/libwebsockets.c
+++ b/lib/libwebsockets.c
@@ -27,6 +27,7 @@
 
 #ifdef LWS_WITH_IPV6
 #if defined(WIN32) || defined(_WIN32)
+#include <wincrypt.h>
 #include <Iphlpapi.h>
 #else
 #include <net/if.h>
diff --git a/test-apps/test-server.h b/test-apps/test-server.h
index 29e67177..892f1e01 100644
--- a/test-apps/test-server.h
+++ b/test-apps/test-server.h
@@ -19,8 +19,14 @@
  */
 
 #if defined(_WIN32) && defined(EXTERNAL_POLL)
+
+#if (WINVER < 0x0600)
+#undef WINVER
+#undef _WIN32_WINNT
 #define WINVER 0x0600
-#define _WIN32_WINNT 0x0600
+#define _WIN32_WINNT WINVER
+#endif
+
 #define poll(fdArray, fds, timeout)  WSAPoll((LPWSAPOLLFD)(fdArray), (ULONG)(fds), (INT)(timeout))
 #endif