diff -urEb openssl-3.5.9.orig/crypto/async/async_local.h openssl-3.5.9/crypto/async/async_local.h
--- openssl-3.5.9.orig/crypto/async/async_local.h	2026-10-22 09:47:14.555901970 +0200
+++ openssl-3.5.9/crypto/async/async_local.h	2026-10-22 12:24:55.463988766 +0200
@@ -17,6 +17,7 @@
 #endif
 
 #if defined(_WIN32)
+#include <winsock2.h>
 #include <windows.h>
 #endif
 
diff -urEb openssl-3.5.9.orig/crypto/cms/cms_lib.c openssl-3.5.9/crypto/cms/cms_lib.c
--- openssl-3.5.9.orig/crypto/cms/cms_lib.c	2026-10-22 09:47:14.558901938 +0200
+++ openssl-3.5.9/crypto/cms/cms_lib.c	2026-10-22 12:29:07.812339312 +0200
@@ -7,6 +7,12 @@
  * https://www.openssl.org/source/license.html
  */
 
+#if defined(_WIN32)
+#  include <winsock2.h>
+#  include <windows.h>
+#  include <wincrypt.h>
+#endif
+
 #include <openssl/asn1t.h>
 #include <openssl/x509v3.h>
 #include <openssl/err.h>
diff -urEb openssl-3.5.9.orig/crypto/mem_sec.c openssl-3.5.9/crypto/mem_sec.c
--- openssl-3.5.9.orig/crypto/mem_sec.c	2026-10-22 09:47:14.564901874 +0200
+++ openssl-3.5.9/crypto/mem_sec.c	2026-10-22 09:50:29.937930234 +0200
@@ -562,7 +562,7 @@
         ret = 2;
 #endif
 
-#if defined(OPENSSL_SYS_LINUX) && defined(MLOCK_ONFAULT) && defined(SYS_mlock2)
+#if defined(OPENSSL_SYS_LINUX) && defined(MLOCK_ONFAULT) && defined(SYS_mlock2) && !defined(__LSB_VERSION__)  // "syscall()" is not available in LSB
     if (syscall(SYS_mlock2, sh.arena, sh.arena_size, MLOCK_ONFAULT) < 0) {
         if (errno == ENOSYS) {
             if (mlock(sh.arena, sh.arena_size) < 0)
diff -urEb openssl-3.5.9.orig/crypto/ml_kem/ml_kem.c openssl-3.5.9/crypto/ml_kem/ml_kem.c
--- openssl-3.5.9.orig/crypto/ml_kem/ml_kem.c	2026-10-22 09:47:14.564901874 +0200
+++ openssl-3.5.9/crypto/ml_kem/ml_kem.c	2026-10-22 13:07:38.748621689 +0200
@@ -26,7 +26,7 @@
 #error "Invalid unequal lengths of ML-KEM shared secret and random inputs"
 #endif
 
-#if UINT_MAX < UINT32_MAX
+#if !defined(_MSC_VER) && (UINT_MAX < UINT32_MAX)
 #error "Unsupported compiler: sizeof(unsigned int) < sizeof(uint32_t)"
 #endif
 
diff -urEb openssl-3.5.9.orig/crypto/pkcs7/pk7_doit.c openssl-3.5.9/crypto/pkcs7/pk7_doit.c
--- openssl-3.5.9.orig/crypto/pkcs7/pk7_doit.c	2026-10-22 09:47:14.567901842 +0200
+++ openssl-3.5.9/crypto/pkcs7/pk7_doit.c	2026-10-22 12:30:30.882791931 +0200
@@ -7,6 +7,12 @@
  * https://www.openssl.org/source/license.html
  */
 
+#if defined(_WIN32)
+#  include <winsock2.h>
+#  include <windows.h>
+#  include <wincrypt.h>
+#endif
+
 #include <stdio.h>
 #include <openssl/rand.h>
 #include <openssl/objects.h>
diff -urEb openssl-3.5.9.orig/crypto/threads_win.c openssl-3.5.9/crypto/threads_win.c
--- openssl-3.5.9.orig/crypto/threads_win.c	2026-10-22 09:47:14.572901788 +0200
+++ openssl-3.5.9/crypto/threads_win.c	2026-10-22 12:24:13.508260522 +0200
@@ -8,6 +8,7 @@
  */
 
 #if defined(_WIN32)
+#include <winsock2.h>
 #include <windows.h>
 #if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x600
 #define USE_RWLOCK
diff -urEb openssl-3.5.9.orig/include/openssl/types.h openssl-3.5.9/include/openssl/types.h
--- openssl-3.5.9.orig/include/openssl/types.h	2026-10-22 09:47:14.593901564 +0200
+++ openssl-3.5.9/include/openssl/types.h	2026-10-22 12:29:01.391381545 +0200
@@ -7,6 +7,13 @@
  * https://www.openssl.org/source/license.html
  */
 
+#if defined(_WIN32)
+/* On MinGW, this prevents a clash with X509_NAME in /usr/share/mingw-w64/include/wincrypt.h */
+#  include <winsock2.h>
+#  include <windows.h>
+#  include <wincrypt.h>
+#endif
+
 /*
  * Unfortunate workaround to avoid symbol conflict with wincrypt.h
  * See https://github.com/openssl/openssl/issues/9981
diff -urEb openssl-3.5.9.orig/providers/implementations/signature/mac_legacy_sig.c openssl-3.5.9/providers/implementations/signature/mac_legacy_sig.c
--- openssl-3.5.9.orig/providers/implementations/signature/mac_legacy_sig.c	2026-10-22 09:47:14.597901521 +0200
+++ openssl-3.5.9/providers/implementations/signature/mac_legacy_sig.c	2026-10-22 13:09:03.601002817 +0200
@@ -10,7 +10,6 @@
 /* We need to use some engine deprecated APIs */
 #define OPENSSL_SUPPRESS_DEPRECATED
 
-#include <stdbool.h>
 #include <openssl/crypto.h>
 #include <openssl/evp.h>
 #include <openssl/core_dispatch.h>
diff -urEb openssl-3.5.9.orig/ssl/rio/rio_notifier.c openssl-3.5.9/ssl/rio/rio_notifier.c
--- openssl-3.5.9.orig/ssl/rio/rio_notifier.c	2026-10-22 09:47:14.598901511 +0200
+++ openssl-3.5.9/ssl/rio/rio_notifier.c	2026-10-22 12:22:04.002093537 +0200
@@ -7,6 +7,10 @@
  * https://www.openssl.org/source/license.html
  */
 
+#if defined(_WIN32)
+#  include "../crypto/bio/bio_local.h"  /* This defines socklen_t */
+#endif
+
 #include "internal/sockets.h"
 #include <openssl/bio.h>
 #include <openssl/err.h>