diff -urN include/openssl.orig/dtls1.h include/openssl/dtls1.h
--- include/openssl.orig/dtls1.h	Mon Sep 21 21:45:45 2015
+++ include/openssl/dtls1.h	Mon Sep 21 21:58:56 2015
@@ -60,7 +60,11 @@
 #ifndef HEADER_DTLS1_H
 #define HEADER_DTLS1_H
 
+#if defined(_WIN32)
+#include <winsock2.h>
+#else
 #include <sys/time.h>
+#endif
 
 #include <stdio.h>
 #include <stdlib.h>
diff -urN include/openssl.orig/opensslconf.h include/openssl/opensslconf.h
--- include/openssl.orig/opensslconf.h	Mon Sep 21 21:45:45 2015
+++ include/openssl/opensslconf.h	Mon Sep 21 21:56:13 2015
@@ -1,6 +1,10 @@
 #include <openssl/opensslfeatures.h>
 /* crypto/opensslconf.h.in */
 
+#if defined(_MSC_VER) && !defined(__attribute__)
+#define __attribute__(a)
+#endif
+
 /* Generate 80386 code? */
 #undef I386_ONLY
 
diff -urN include/openssl.orig/ossl_typ.h include/openssl/ossl_typ.h
--- include/openssl.orig/ossl_typ.h	Mon Sep 21 21:45:45 2015
+++ include/openssl/ossl_typ.h	Mon Sep 21 21:56:22 2015
@@ -100,6 +100,22 @@
 typedef struct ASN1_ITEM_st ASN1_ITEM;
 typedef struct asn1_pctx_st ASN1_PCTX;
 
+#if defined(_WIN32) && defined(__WINCRYPT_H__)
+#ifndef LIBRESSL_INTERNAL
+#ifdef _MSC_VER
+#pragma message("Warning, overriding WinCrypt defines")
+#else
+#warning overriding WinCrypt defines
+#endif
+#endif
+#undef X509_NAME
+#undef X509_CERT_PAIR
+#undef X509_EXTENSIONS
+#undef OCSP_REQUEST
+#undef OCSP_RESPONSE
+#undef PKCS7_ISSUER_AND_SERIAL
+#endif
+
 #ifdef BIGNUM
 #undef BIGNUM
 #endif
diff -urN include/openssl.orig/pkcs7.h include/openssl/pkcs7.h
--- include/openssl.orig/pkcs7.h	Mon Sep 21 21:45:45 2015
+++ include/openssl/pkcs7.h	Mon Sep 21 21:56:29 2015
@@ -69,6 +69,18 @@
 extern "C" {
 #endif
 
+#if defined(_WIN32) && defined(__WINCRYPT_H__)
+#ifndef LIBRESSL_INTERNAL
+#ifdef _MSC_VER
+#pragma message("Warning, overriding WinCrypt defines")
+#else
+#warning overriding WinCrypt defines
+#endif
+#endif
+#undef PKCS7_ISSUER_AND_SERIAL
+#undef PKCS7_SIGNER_INFO
+#endif
+
 /*
 Encryption_ID		DES-CBC
 Digest_ID		MD5
diff -urN include/openssl.orig/x509.h include/openssl/x509.h
--- include/openssl.orig/x509.h	Mon Sep 21 21:45:45 2015
+++ include/openssl/x509.h	Mon Sep 21 21:56:35 2015
@@ -112,6 +112,19 @@
 extern "C" {
 #endif
 
+#if defined(_WIN32)
+#ifndef LIBRESSL_INTERNAL
+#ifdef _MSC_VER
+#pragma message("Warning, overriding WinCrypt defines")
+#else
+#warning overriding WinCrypt defines
+#endif
+#endif
+#undef X509_NAME
+#undef X509_CERT_PAIR
+#undef X509_EXTENSIONS
+#endif
+
 #define X509_FILETYPE_PEM	1
 #define X509_FILETYPE_ASN1	2
 #define X509_FILETYPE_DEFAULT	3