diff --git a/rowers/dataprep.py b/rowers/dataprep.py
index b1871fc9..44dbb856 100644
--- a/rowers/dataprep.py
+++ b/rowers/dataprep.py
@@ -1846,9 +1846,16 @@ def get_startdate_time_zone(r,row,startdatetime=None):
             timezone_str = pendulum.instance(startdatetime).timezone.name
         except ValueError:
             timezone_str = 'Ect/GMT'
+    elif startdatetime == '':
+        startdatetime = row.rowdatetime
     else:
         startdatetime = row.rowdatetime
 
+    try:
+        tz = startdatetime.tzinfo
+    except AttributeError:
+        startdatetime = row.rowdatetime
+
     partofday = getpartofday(row,r)
 
     if startdatetime.tzinfo is None or str(startdatetime.tzinfo) in ['tzutc()','Ect/GMT']: