diff --git a/src/disk/mo.c b/src/disk/mo.c
index a5adbb108..13715947a 100644
--- a/src/disk/mo.c
+++ b/src/disk/mo.c
@@ -22,6 +22,7 @@
 #include <string.h>
 #include <stdlib.h>
 #include <stdarg.h>
+#include <unistd.h>
 #include <wchar.h>
 #define HAVE_STDARG_H
 #include <86box/86box.h>
@@ -42,7 +43,7 @@
 #include <windows.h>
 #include <io.h>
 #else
-#include <unistd.h>
+#include <errno.h>
 #endif
 
 mo_drive_t	mo_drives[MO_NUM];
@@ -1041,46 +1042,41 @@ mo_format(mo_t *dev)
 {
     unsigned long size;
     int ret;
-    int fd;
+    int fd = fileno(dev->drv->f);
+    int64_t liSize = 0;
 
     mo_log("MO %i: Formatting media...\n", dev->id);
 
+    if (fd == -1) {
+        mo_log("MO %i: Failed to get file descriptor.\n", dev->id);
+        return;
+    }
+
     fseek(dev->drv->f, 0, SEEK_END);
     size = (uint32_t) ftello64(dev->drv->f);
 
-    HANDLE fh;
-    LARGE_INTEGER liSize;
+    errno = 0;
+    rewind(dev->drv->f);
 
-    fd = _fileno(dev->drv->f);
-    fh = (HANDLE)_get_osfhandle(fd);
-
-    liSize.QuadPart = 0;
-
-    ret = (int)SetFilePointerEx(fh, liSize, NULL, FILE_BEGIN);
-
-    if (!ret) {
+    if (errno) {
 	mo_log("MO %i: Failed seek to start of image file\n", dev->id);
 	return;
     }
 
-    ret = (int)SetEndOfFile(fh);
-
-    if (!ret) {
+    ret = ftruncate(fd, 0);
+    if (ret == -1) {
 	mo_log("MO %i: Failed to truncate image file to 0\n", dev->id);
 	return;
     }
 
-    liSize.QuadPart = size;
-    ret = (int)SetFilePointerEx(fh, liSize, NULL, FILE_BEGIN);
-
-    if (!ret) {
+    liSize = size;
+    ret = fseek(dev->drv->f, 0, SEEK_END);
+    if (ret == -1) {
 	mo_log("MO %i: Failed seek to end of image file\n", dev->id);
 	return;
     }
-
-    ret = (int)SetEndOfFile(fh);
-
-    if (!ret) {
+    ret = ftruncate(fd, liSize);
+    if (ret == -1) {
 	mo_log("MO %i: Failed to truncate image file to %llu\n", dev->id, size);
 	return;
     }