diff --git a/extension/data_loader/file_data_loader.cpp b/extension/data_loader/file_data_loader.cpp
index 1d097cfd989..1a9ddad259f 100644
--- a/extension/data_loader/file_data_loader.cpp
+++ b/extension/data_loader/file_data_loader.cpp
@@ -14,10 +14,10 @@
 #include <cstring>
 #include <limits>
 
+#include <executorch/runtime/platform/compat_unistd.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
-#include <unistd.h>
 
 #include <executorch/runtime/core/error.h>
 #include <executorch/runtime/core/result.h>
@@ -71,6 +71,9 @@ FileDataLoader::~FileDataLoader() {
   std::free(const_cast<char*>(file_name_));
   // fd_ can be -1 if this instance was moved from, but closing a negative fd is
   // safe (though it will return an error).
+  if (fd_ == -1) {
+    return;
+  }
   ::close(fd_);
 }
 
diff --git a/runtime/platform/compat_unistd.h b/runtime/platform/compat_unistd.h
new file mode 100644
index 00000000000..c8bc4866702
--- /dev/null
+++ b/runtime/platform/compat_unistd.h
@@ -0,0 +1,75 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+/**
+ * @file
+ * unistd.h related macros for POSIX/Windows compatibility.
+ */
+#pragma once
+
+#if defined(_WIN32) && !defined(_WIN64)
+#error \
+    "You're trying to build ExecuTorch with a too old version of Windows. We need Windows 64-bit."
+#endif
+
+#if !defined(_WIN64)
+#include <unistd.h>
+#else
+#include <io.h>
+#define O_RDONLY _O_RDONLY
+#define open _open
+#define close _close
+#define read _read
+#define write _write
+#define stat _stat64
+#define fstat _fstat64
+#define off_t _off_t
+#define lseek _lseeki64
+
+#include <executorch/runtime/platform/compiler.h> // For ssize_t.
+#include <windows.h>
+// To avoid conflicts with std::numeric_limits<int32_t>::max() in
+// file_data_loader.cpp.
+#undef max
+
+inline ssize_t pread(int fd, void* buf, size_t nbytes, size_t offset) {
+  OVERLAPPED overlapped; /* The offset for ReadFile. */
+  memset(&overlapped, 0, sizeof(overlapped));
+  overlapped.Offset = offset;
+  overlapped.OffsetHigh = offset >> 32;
+
+  BOOL result; /* The result of ReadFile. */
+  DWORD bytes_read; /* The number of bytes read. */
+  HANDLE file = (HANDLE)_get_osfhandle(fd);
+
+  result = ReadFile(file, buf, nbytes, &bytes_read, &overlapped);
+  DWORD error = GetLastError();
+  if (!result) {
+    if (error == ERROR_IO_PENDING) {
+      result = GetOverlappedResult(file, &overlapped, &bytes_read, TRUE);
+      if (!result) {
+        error = GetLastError();
+      }
+    }
+  }
+  if (!result) {
+    // Translate error into errno.
+    switch (error) {
+      case ERROR_HANDLE_EOF:
+        errno = 0;
+        break;
+      default:
+        errno = EIO;
+        break;
+    }
+    return -1;
+  }
+  return bytes_read;
+}
+
+#endif // !defined(_WIN64)
\ No newline at end of file
diff --git a/runtime/platform/targets.bzl b/runtime/platform/targets.bzl
index 42bb851e2cf..68322ffe97f 100644
--- a/runtime/platform/targets.bzl
+++ b/runtime/platform/targets.bzl
@@ -68,6 +68,7 @@ def define_common_targets():
             "log.h",
             "profiler.h",
             "runtime.h",
+            "compat_unistd.h",
         ],
         srcs = [
             "abort.cpp",