From ea29c35b23681778f80fe59ee35db4e8c31b6704 Mon Sep 17 00:00:00 2001
From: Pey Lian Lim <lim@stsci.edu>
Date: Mon, 20 Feb 2017 14:25:02 -0500
Subject: [PATCH] Avoid KeyError in RTD build [skip ci]

---
 pysynphot/locations.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pysynphot/locations.py b/pysynphot/locations.py
index 5dba590b..9aa019c7 100644
--- a/pysynphot/locations.py
+++ b/pysynphot/locations.py
@@ -47,6 +47,7 @@
                   "crippled.")
     rootdir = ''
 
+ftp_rootdir = 'ftp://ftp.stsci.edu/cdbs'
 
 # Data directory is now installed locally
 specdir = os.path.join(os.path.dirname(__file__), 'data')
@@ -301,8 +302,9 @@ def get_latest_file(template, raise_error=False, err_msg=''):
 
 
 def _refTable(template):
-    return get_latest_file(os.path.join(os.environ['PYSYN_CDBS'], template),
-                           raise_error=True)
+    return get_latest_file(
+        os.path.join(os.environ.get('PYSYN_CDBS', ftp_rootdir), template),
+        raise_error=True)
 
 RedLaws = {}