diff --git a/lib/vtls/openssl.c b/lib/vtls/openssl.c
index 4bfd040d3..25b7dfab8 100644
--- a/lib/vtls/openssl.c
+++ b/lib/vtls/openssl.c
@@ -34,6 +34,13 @@
 /* Wincrypt must be included before anything that could include OpenSSL. */
 #if defined(USE_WIN32_CRYPTO)
 #include <wincrypt.h>
+/* Undefine wincrypt conflicting symbols for BoringSSL. */
+#undef X509_NAME
+#undef X509_EXTENSIONS
+#undef PKCS7_ISSUER_AND_SERIAL
+#undef PKCS7_SIGNER_INFO
+#undef OCSP_REQUEST
+#undef OCSP_RESPONSE
 #endif
 
 #include "urldata.h"