diff --git a/xray/data_array.py b/xray/data_array.py
index 2397340b57a..2d2cc760dc1 100644
--- a/xray/data_array.py
+++ b/xray/data_array.py
@@ -704,8 +704,7 @@ def concat(cls, arrays, dimension='concat_dimension', indexers=None,
             concat_over = set()
         elif isinstance(concat_over, basestring):
             concat_over = set([concat_over])
-        else:
-            concat_over = set(concat_over) | set([name])
+        concat_over = set(concat_over) | set([name])
         ds = xray.Dataset.concat(datasets, dimension, indexers,
                                      concat_over=concat_over)
         return ds[name]