diff --git a/doc/THANKS b/doc/THANKS
index 06bd4ee38..aebb1cda1 100644
--- a/doc/THANKS
+++ b/doc/THANKS
@@ -541,6 +541,9 @@ buawig <buawig@gmail.com>
 Bugtrace <bugtrace@gmail.com>
     for reporting several bugs
 
+Christian S. <christian_s@linuxmail.org>
+    for reporting a minor bug
+
 clav <elclav@gmail.com>
     for reporting a minor bug
 
diff --git a/lib/core/common.py b/lib/core/common.py
index b6a471192..b834c11d7 100644
--- a/lib/core/common.py
+++ b/lib/core/common.py
@@ -2785,7 +2785,7 @@ def safeCSValue(value):
 
     retVal = value
 
-    if isinstance(retVal, basestring):
+    if retVal and isinstance(retVal, basestring):
         if not (retVal[0] == retVal[-1] == '"'):
             if any(map(lambda x: x in retVal, ['"', ',', '\n'])):
                 retVal = '"%s"' % retVal.replace('"', '""')