--- qemu-0.9.0.20070921/block.c.orig	2007-09-23 17:04:21.000000000 +0200
+++ qemu-0.9.0.20070921/block.c	2007-09-23 17:18:39.000000000 +0200
@@ -349,7 +349,19 @@
         bdrv_delete(bs1);
 
         get_tmp_filename(tmp_filename, sizeof(tmp_filename));
-        realpath(filename, backing_filename);
+        if (realpath(filename, backing_filename) == NULL) {
+            if (strstart(filename, "fat:", NULL)) {
+                int i = strrchr(filename, ':') - filename;
+
+                if ((filename[i-2] == ':') && isalpha(filename[i-1]))
+                    i -= 1; /* workaround for DOS drive names */
+                else
+                    i += 1;
+
+                strncpy(backing_filename, filename, i);
+                realpath(filename + i, backing_filename + i);
+            }
+        }
         if (bdrv_create(&bdrv_qcow2, tmp_filename,
                         total_size, backing_filename, 0) < 0) {
             return -1;