diff --git a/src/disk.sh b/src/disk.sh
index c479d8f..ab4eebf 100644
--- a/src/disk.sh
+++ b/src/disk.sh
@@ -611,7 +611,11 @@ if [ -z "$DISK_FMT" ]; then
   if [ -f "$DISK1_FILE.qcow2" ]; then
     DISK_FMT="qcow2"
   else
-    DISK_FMT="raw"
+    if [[ "$BOOT" ==  *".qcow2" ]] && [ ! -f "$DISK1_FILE.img" ]; then
+      DISK_FMT="qcow2"
+    else
+      DISK_FMT="raw"
+    fi
   fi
 fi