diff --git a/pym/builder/variables/builder.py b/pym/builder/variables/builder.py
index fe13e5b..f6f2622 100644
--- a/pym/builder/variables/builder.py
+++ b/pym/builder/variables/builder.py
@@ -752,13 +752,14 @@ class VariableClBuilderImageFilename(Variable):
         self.help = _("set image path")
 
     def check(self, value):
-        if not value:
-            raise VariableError(_("You must specify image filename"))
-        for line in process("/bin/losetup", "-j", value):
-            lodev, op, line = line.partition(":")
-            if lodev:
-                raise VariableError(
-                    _("Image %s is already used") % value)
+        if self.Get('cl_builder_id'):
+            if not value:
+                raise VariableError(_("You must specify image filename"))
+            for line in process("/bin/losetup", "-j", value):
+                lodev, op, line = line.partition(":")
+                if lodev:
+                    raise VariableError(
+                        _("Image %s is already used") % value)
 
     def _isoname(self, dn, rewrite=False):
         shortname = self.Get('os_builder_linux_shortname').lower()