diff --git a/block-qcow.c b/block-qcow.c
index 730ae67ed8f7095ca4d22e80aca57678be18fb6c..0ac2b42b4fdf0b30a7a4e60ac2cf48a77a1bbe12 100644
--- a/block-qcow.c
+++ b/block-qcow.c
@@ -752,11 +752,15 @@ static int qcow_create(const char *filename, int64_t total_size,
     header_size = sizeof(header);
     backing_filename_len = 0;
     if (backing_file) {
-        header.backing_file_offset = cpu_to_be64(header_size);
-        backing_filename_len = strlen(backing_file);
-        header.backing_file_size = cpu_to_be32(backing_filename_len);
-        header_size += backing_filename_len;
-        header.mtime = cpu_to_be32(0);
+        if (strcmp(backing_file, "fat:")) {
+            header.backing_file_offset = cpu_to_be64(header_size);
+            backing_filename_len = strlen(backing_file);
+            header.backing_file_size = cpu_to_be32(backing_filename_len);
+            header_size += backing_filename_len;
+        } else {
+            /* special backing file for vvfat */
+            backing_file = NULL;
+        }
         header.cluster_bits = 9; /* 512 byte cluster to avoid copying
                                     unmodifyed sectors */
         header.l2_bits = 12; /* 32 KB L2 tables */