From 6e9826bec1233c77b6c3796cae0a100e693711a2 Mon Sep 17 00:00:00 2001
From: Max Ghenis <mghenis@gmail.com>
Date: Sat, 27 Feb 2021 09:59:34 -0800
Subject: [PATCH] Add back check for null columns

---
 scf/load.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/scf/load.py b/scf/load.py
index 336b65c..1d1bfd5 100644
--- a/scf/load.py
+++ b/scf/load.py
@@ -70,7 +70,8 @@ def load(
     :rtype: Union[pd.DataFrame, mdf.MicroDataFrame]
     """
     # Make cols a list if a single column is passed.
-    columns = mdf.listify(columns)
+    if columns is not None:
+        columns = mdf.listify(columns)
     # If years is a single year rather than a list, don't use a loop.
     if isinstance(years, int):
         res = load_single_scf(years, columns)