diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2e26c4ff47..314674842d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -796,6 +796,9 @@ if(MSVC)
   set(EXE_CFLAGS "${EXE_CFLAGS}")
 else()
   set(EXE_CFLAGS "${EXE_CFLAGS} -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -D_GNU_SOURCE -fno-exceptions -fno-rtti  -Werror=strict-prototypes -Werror=old-style-definition -Werror=type-limits -Wno-missing-braces")
+  if(MINGW)
+      set(EXE_CFLAGS "${EXE_CFLAGS} -D__USE_MINGW_ANSI_STDIO -Wno-pedantic-ms-format")
+  endif()
 endif()
 
 set(BLAKE_CFLAGS "-std=c99")
diff --git a/example/hello_world/hello_windows.zig b/example/hello_world/hello_windows.zig
index f55db2edeb..8016c3c490 100644
--- a/example/hello_world/hello_windows.zig
+++ b/example/hello_world/hello_windows.zig
@@ -1,5 +1,7 @@
 use @import("std").os.windows;
 
+extern "user32" stdcallcc fn MessageBoxA(hWnd: ?HANDLE, lpText: ?LPCTSTR, lpCaption: ?LPCTSTR, uType: UINT) c_int;
+
 export fn WinMain(hInstance: HINSTANCE, hPrevInstance: HINSTANCE, lpCmdLine: PWSTR, nCmdShow: INT) INT {
     _ = MessageBoxA(null, c"hello", c"title", 0);
     return 0;
diff --git a/src/os.cpp b/src/os.cpp
index 431f7d16b4..6c620fae2e 100644
--- a/src/os.cpp
+++ b/src/os.cpp
@@ -23,6 +23,14 @@
 #define WIN32_LEAN_AND_MEAN
 #endif
 
+#if !defined(_WIN32_WINNT)
+#define _WIN32_WINNT 0x600
+#endif
+
+#if !defined(NTDDI_VERSION)
+#define NTDDI_VERSION 0x06000000
+#endif
+
 #include <windows.h>
 #include <shlobj.h>
 #include <io.h>
@@ -1634,16 +1642,16 @@ static Optional<uint32_t> Utf16LeIterator_nextCodepoint(Utf16LeIterator *it) {
     if (it->bytes[it->i] == 0 && it->bytes[it->i + 1] == 0)
         return {};
     uint32_t c0 = ((uint32_t)it->bytes[it->i]) | (((uint32_t)it->bytes[it->i + 1]) << 8);
-    if (c0 & ~((uint32_t)0x03ff) == 0xd800) {
+    if ((c0 & ~((uint32_t)0x03ff)) == 0xd800) {
         // surrogate pair
         it->i += 2;
         assert(it->bytes[it->i] != 0 || it->bytes[it->i + 1] != 0);
         uint32_t c1 = ((uint32_t)it->bytes[it->i]) | (((uint32_t)it->bytes[it->i + 1]) << 8);
-        assert(c1 & ~((uint32_t)0x03ff) == 0xdc00);
+        assert((c1 & ~((uint32_t)0x03ff)) == 0xdc00);
         it->i += 2;
         return Optional<uint32_t>::some(0x10000 + (((c0 & 0x03ff) << 10) | (c1 & 0x03ff)));
     } else {
-        assert(c0 & ~((uint32_t)0x03ff) != 0xdc00);
+        assert((c0 & ~((uint32_t)0x03ff)) != 0xdc00);
         it->i += 2;
         return Optional<uint32_t>::some(c0);
     }
@@ -1714,7 +1722,7 @@ static void utf16le_ptr_to_utf8(Buf *out, WCHAR *utf16le) {
 // Ported from std.os.getAppDataDir
 Error os_get_app_data_dir(Buf *out_path, const char *appname) {
 #if defined(ZIG_OS_WINDOWS)
-    Error err;
+    // Error err;
     WCHAR *dir_path_ptr;
     switch (SHGetKnownFolderPath(FOLDERID_LocalAppData, KF_FLAG_CREATE, nullptr, &dir_path_ptr)) {
         case S_OK:
@@ -1928,7 +1936,8 @@ Error os_file_mtime(OsFile file, OsTimeStamp *mtime) {
     FILETIME last_write_time;
     if (!GetFileTime(file, nullptr, nullptr, &last_write_time))
         return ErrorUnexpected;
-    mtime->sec = last_write_time.dwLowDateTime | (last_write_time.dwHighDateTime << 32);
+    // mtime->sec = last_write_time.dwLowDateTime | (last_write_time.dwHighDateTime << 32);
+    mtime->sec = (((ULONGLONG) last_write_time.dwHighDateTime) << 32) + last_write_time.dwLowDateTime;
     mtime->nsec = 0;
     return ErrorNone;
 #elif defined(ZIG_OS_LINUX)
@@ -2007,11 +2016,12 @@ Error os_file_read_all(OsFile file, Buf *contents) {
 
 Error os_file_overwrite(OsFile file, Buf *contents) {
 #if defined(ZIG_OS_WINDOWS)
+    DWORD bytes_written;
     if (SetFilePointer(file, 0, nullptr, FILE_BEGIN) == INVALID_SET_FILE_POINTER)
         return ErrorFileSystem;
     if (!SetEndOfFile(file))
         return ErrorFileSystem;
-    if (!WriteFile(file, buf_ptr(contents), buf_len(contents), nullptr, nullptr))
+    if (!WriteFile(file, buf_ptr(contents), buf_len(contents), &bytes_written, nullptr))
         return ErrorFileSystem;
     return ErrorNone;
 #else
diff --git a/src/windows_com.hpp b/src/windows_com.hpp
index 4c807218c0..f9833e0912 100644
--- a/src/windows_com.hpp
+++ b/src/windows_com.hpp
@@ -28,6 +28,9 @@
 #include <io.h>
 #include <shellapi.h>
 
+// Standard headers
+#include <stdio.h>
+
 // COM support header files
 #include <comdef.h>