diff --git a/CMakeLists.txt b/CMakeLists.txt
index d39958a..ba21f3c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -117,8 +117,14 @@ if(BUILD_SHARED_LIBS AND WIN32 AND HTTPLIB_COMPILE)
 	set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS ON)
 endif()
 
-if(CMAKE_SYSTEM_NAME MATCHES "Windows" AND ${CMAKE_SYSTEM_VERSION} VERSION_LESS "10.0.0")
-	message(SEND_ERROR "Windows ${CMAKE_SYSTEM_VERSION} or lower is not supported. Please use Windows 10 or later.")
+if(CMAKE_SYSTEM_NAME MATCHES "Windows")
+    if(CMAKE_SYSTEM_VERSION)
+        if(${CMAKE_SYSTEM_VERSION} VERSION_LESS "10.0.0")
+            message(SEND_ERROR "Windows ${CMAKE_SYSTEM_VERSION} or lower is not supported. Please use Windows 10 or later.")
+        endif()
+    else()
+        message(WARNING "Cross-compiling for Windows, but CMAKE_SYSTEM_VERSION is not specified. Assuming target is Windows 10 or later.")
+    endif()
 endif()
 if(CMAKE_SIZEOF_VOID_P LESS 8)
 	message(WARNING "Pointer size ${CMAKE_SIZEOF_VOID_P} is not supported. Please use a 64-bit compiler.")
diff --git a/httplib.h b/httplib.h
index e15ba44..728504a 100644
--- a/httplib.h
+++ b/httplib.h
@@ -3083,8 +3083,13 @@ inline bool mmap::open(const char *path) {
   auto wpath = u8string_to_wstring(path);
   if (wpath.empty()) { return false; }
 
+#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP | WINAPI_PARTITION_SYSTEM | WINAPI_PARTITION_GAMES) && (_WIN32_WINNT >= _WIN32_WINNT_WIN8)
   hFile_ = ::CreateFile2(wpath.c_str(), GENERIC_READ, FILE_SHARE_READ,
                          OPEN_EXISTING, NULL);
+#else
+  hFile_ = ::CreateFileW(wpath.c_str(), GENERIC_READ, FILE_SHARE_READ, NULL,
+                        OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+#endif
 
   if (hFile_ == INVALID_HANDLE_VALUE) { return false; }