diff --git a/lib/ldap.c b/lib/ldap.c
index 51a32dc964..410dc72e8a 100644
--- a/lib/ldap.c
+++ b/lib/ldap.c
@@ -37,6 +37,18 @@
  * OpenLDAP library versions, USE_OPENLDAP shall not be defined.
  */
 
+/* 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
+
 #ifdef USE_WIN32_LDAP           /* Use Windows LDAP implementation. */
 # include <winldap.h>
 # ifndef LDAP_VENDOR_NAME
diff --git a/lib/vtls/schannel.h b/lib/vtls/schannel.h
index 0b4c4d9344..05323c7a7e 100644
--- a/lib/vtls/schannel.h
+++ b/lib/vtls/schannel.h
@@ -28,6 +28,18 @@
 
 #ifdef USE_SCHANNEL
 
+/* 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 <schnlsp.h>
 #include <schannel.h>
 #include "curl_sspi.h"