diff --git a/poky/meta/classes/testimage.bbclass b/poky/meta/classes/testimage.bbclass
index 9bb5a5c..525c5a6 100644
--- a/poky/meta/classes/testimage.bbclass
+++ b/poky/meta/classes/testimage.bbclass
@@ -210,7 +210,11 @@
             bb.fatal('Unsupported image type built. Add a comptible image to '
                      'IMAGE_FSTYPES. Supported types: %s' %
                      ', '.join(supported_fstypes))
-    rootfs = '%s.%s' % (image_name, fstypes[0])
+    qfstype = fstypes[0]
+    qdeffstype = d.getVar("QB_DEFAULT_FSTYPE")
+    if qdeffstype:
+        qfstype = qdeffstype
+    rootfs = '%s.%s' % (image_name, qfstype)
 
     # Get tmpdir (not really used, just for compatibility)
     tmpdir = d.getVar("TMPDIR")