--- a/src/os/win32/ngx_files.c
+++ b/src/os/win32/ngx_files.c
@@ -6,26 +6,49 @@
 ssize_t ngx_read_file(ngx_file_t *file, char *buf, size_t size, off_t offset)
 {
     size_t      n;
-    long        high_offset;
-    ngx_err_t   err;
     OVERLAPPED  ovlp, *povlp;
 
+#if (WIN9X)
+
     if (ngx_win32_version < NGX_WIN_NT) {
-        high_offset = (long) (offset >> 32);
-        if (SetFilePointer(file->fd, (long) offset, &high_offset, FILE_BEGIN)
-                                                                 == 0xFFFFFFFF)
-        {
-            err = ngx_errno;
-            if (err != NO_ERROR) {
-                ngx_log_error(NGX_LOG_ERR, file->log, err,
-                              "SeekFilePointer() failed");
-                return NGX_ERROR;
+        long        high_offset;
+        ngx_err_t   err;
+
+        /*
+         * in Win9X the overlapped pointer must be NULL
+         * so we need to use SetFilePointer() to set the offset
+         */
+
+        if (file->offset != offset) {
+
+            /*
+             * the maximum file size on FAT16 is 2G, but on FAT32 it's 4G so we
+             * need to use high_offset because a single offset is signed value
+             */
+
+            high_offset = (long) (offset >> 32);
+            if (SetFilePointer(file->fd, (long) offset, &high_offset,
+                               FILE_BEGIN) == INVALID_SET_FILE_POINTER)
+            {
+                /*
+                 * INVALID_SET_FILE_POINTER is 0xffffffff and it can be valid
+                 * value for large file so we need also to check GetLastError()
+                 */
+
+                err = ngx_errno;
+                if (err != NO_ERROR) {
+                    ngx_log_error(NGX_LOG_ERR, file->log, err,
+                                  "SeekFilePointer() failed");
+                    return NGX_ERROR;
+                }
             }
         }
 
         povlp = NULL;
 
     } else {
+
+#endif
         ovlp.Internal = 0;
         ovlp.InternalHigh = 0;
         ovlp.Offset = (DWORD) offset;
@@ -33,7 +56,10 @@ ssize_t ngx_read_file(ngx_file_t *file, 
         ovlp.hEvent = NULL;
 
         povlp = &ovlp;
+
+#if (WIN9X)
     }
+#endif
 
     if (ReadFile(file->fd, buf, size, &n, povlp) == 0) {
         ngx_log_error(NGX_LOG_ERR, file->log, ngx_errno, "ReadFile() failed");
@@ -46,13 +72,66 @@ ssize_t ngx_read_file(ngx_file_t *file, 
 }
 
 
-/* TODO: as read file */
-
 ssize_t ngx_write_file(ngx_file_t *file, char *buf, size_t size, off_t offset)
 {
-    size_t n;
+    size_t      n;
+    OVERLAPPED  ovlp, *povlp;
+
+#if (WIN9X)
+
+    if (ngx_win32_version < NGX_WIN_NT) {
+        long        high_offset;
+        ngx_err_t   err;
+
+        /*
+         * in Win9X the overlapped pointer must be NULL
+         * so we need to use SetFilePointer() to set the offset
+         */
+
+        if (file->offset != offset) {
+
+            /*
+             * the maximum file size on FAT16 is 2G, but on FAT32 it's 4G so we
+             * need to use high_offset because a single offset is signed value
+             */
 
-    if (WriteFile(file->fd, buf, size, &n, NULL) == 0) {
+            high_offset = (long) (offset >> 32);
+            if (SetFilePointer(file->fd, (long) offset, &high_offset,
+                               FILE_BEGIN) == INVALID_SET_FILE_POINTER)
+            {
+                /*
+                 * INVALID_SET_FILE_POINTER is 0xffffffff and it can be valid
+                 * value for large file so we need also to check GetLastError()
+                 */
+
+                err = ngx_errno;
+                if (err != NO_ERROR) {
+                    ngx_log_error(NGX_LOG_ERR, file->log, err,
+                                  "SeekFilePointer() failed");
+                    return NGX_ERROR;
+                }
+            }
+        }
+
+        povlp = NULL;
+
+    } else {
+
+#endif
+
+        ovlp.Internal = 0;
+        ovlp.InternalHigh = 0;
+        ovlp.Offset = (DWORD) offset;
+        ovlp.OffsetHigh = (DWORD) (offset >> 32);
+        ovlp.hEvent = NULL;
+
+        povlp = &ovlp;
+
+#if (WIN9X)
+    }
+#endif
+
+    if (WriteFile(file->fd, buf, size, &n, povlp) == 0) {
         ngx_log_error(NGX_LOG_ERR, file->log, ngx_errno, "WriteFile() failed");
         return NGX_ERROR;
     }
@@ -63,12 +142,15 @@ ssize_t ngx_write_file(ngx_file_t *file,
 }
 
 
-/* TODO: log error */
-
 int ngx_file_append_mode(ngx_fd_t fd)
 {
-    if (SetFilePointer(fd, 0, NULL, FILE_END) == 0xFFFFFFFF) {
-        if (GetLastError() != NO_ERROR) {
+    ngx_err_t  err;
+
+    if (SetFilePointer(fd, 0, NULL, FILE_END) == INVALID_SET_FILE_POINTER) {
+        err = ngx_errno;
+        if (err != NO_ERROR) {
+            ngx_log_error(NGX_LOG_ERR, file->log, err,
+                          "SeekFilePointer() failed");
             return NGX_ERROR;
         }
     }