diff --git a/pandas/core/strings.py b/pandas/core/strings.py
index 53d46fa46811d..58ce562d03d1d 100644
--- a/pandas/core/strings.py
+++ b/pandas/core/strings.py
@@ -2237,7 +2237,7 @@ def cat(self, others=None, sep=None, na_rep=None, join=None):
             # Need to add keys for uniqueness in case of duplicate columns
             others = concat(others, axis=1,
                             join=(join if join == 'inner' else 'outer'),
-                            keys=range(len(others)), copy=False)
+                            keys=range(len(others)), sort=False, copy=False)
             data, others = data.align(others, join=join)
             others = [others[x] for x in others]  # again list of Series