diff --git a/test/test_option_calculation.py b/test/test_option_calculation.py
index eebbd3a..b655bc4 100644
--- a/test/test_option_calculation.py
+++ b/test/test_option_calculation.py
@@ -447,6 +447,24 @@ def test_callback_master_and_slaves_master():
     assert cfg.val1.val2 == [None, None]
 
 
+def test_callback_slave():
+    val1 = StrOption('val1', "", multi=True)
+    val2 = StrOption('val2', "", multi=True, callback=return_value, callback_params={'': (['string', 'new'],)})
+    interface1 = OptionDescription('val1', '', [val1, val2])
+    interface1.impl_set_group_type(groups.master)
+    maconfig = OptionDescription('rootconfig', '', [interface1])
+    cfg = Config(maconfig)
+    cfg.read_write()
+    cfg.val1.val1 = ['val']
+    assert cfg.val1.val2 == ['string']
+    cfg.val1.val1 = ['val', 'val1']
+    assert cfg.val1.val2 == ['string', 'new']
+    cfg.val1.val1 = ['val', 'val1', 'val2']
+    assert cfg.val1.val2 == ['string', 'new', None]
+    cfg.val1.val1 = ['val', 'val1', 'val2', 'val3']
+    assert cfg.val1.val2 == ['string', 'new', None, None]
+
+
 def test_callback_master_and_slaves_master2():
     val1 = StrOption('val1', "", multi=True)
     val2 = StrOption('val2', "", multi=True, default_multi='val2')
diff --git a/tiramisu/autolib.py b/tiramisu/autolib.py
index bb7698f..1f86e54 100644
--- a/tiramisu/autolib.py
+++ b/tiramisu/autolib.py
@@ -236,7 +236,6 @@ def carry_out_calculation(option, context, callback, callback_params,
                 if index < len(ret):
                     ret = ret[index]
                 else:
-                    #FIXME really?
                     ret = None
             else:
                 raise SlaveError(_("callback cannot return a list for a "