diff --git a/rowers/dataprep.py b/rowers/dataprep.py
index a02c5ce3..9368c961 100644
--- a/rowers/dataprep.py
+++ b/rowers/dataprep.py
@@ -1188,7 +1188,10 @@ def save_workout_database(f2, r, dosmooth=True, workouttype='rower',
     if workouttype in otetypes:
         dragfactor = row.dragfactor
 
+
     t = datetime.datetime.strptime(duration, "%H:%M:%S.%f")
+
+
     delta = datetime.timedelta(
         hours=t.hour, minutes=t.minute, seconds=t.second)
 
diff --git a/rowers/tests/test_unit_tests.py b/rowers/tests/test_unit_tests.py
index 56cf7b56..1a8f6d27 100644
--- a/rowers/tests/test_unit_tests.py
+++ b/rowers/tests/test_unit_tests.py
@@ -5,7 +5,7 @@ from __future__ import unicode_literals
 
 from .statements import *
 from rowers.mytypes import rowtypes
-from rowers.utils import allmonths,allsundays
+from rowers.utils import allmonths,allsundays, totaltime_sec_to_string
 from rowers.models import update_records
 
 from django.db import transaction
@@ -94,6 +94,25 @@ class OtherUnitTests(TestCase):
         # time zone should be US/Pacific
         self.assertTrue('US/Pacific' in str(startdate.tzinfo))
 
+    def test_totaltime_sec_to_string(self):
+        results = (
+            (0,"0:00"),
+            (120,"2:00"),
+            (3634.2,"1:00:34"),
+        )
+
+        for duration, expected in results:
+            self.assertEqual(totaltime_sec_to_string(duration, shorten=True), expected)
+
+        results = (
+            (0,"00:00:00.0"),
+            (120,"00:02:00.0"),
+            (3634.2,"01:00:34.2"),
+        )
+
+        for duration, expected in results:
+            self.assertEqual(totaltime_sec_to_string(duration, shorten=False), expected)
+
 
 
     def test_summaryfromsplitdata(self):
diff --git a/rowers/utils.py b/rowers/utils.py
index 4f70f43b..7572d7f5 100644
--- a/rowers/utils.py
+++ b/rowers/utils.py
@@ -428,32 +428,77 @@ def wavg(group, avg_name, weight_name):
     except ZeroDivisionError:  # pragma: no cover
         return d.mean()
 
+from string import Formatter
 
 def totaltime_sec_to_string(totaltime, shorten=False):
+    if np.isnan(totaltime):
+        return ''
+
+    fmt = '{H:02}:{M:02}:{S:02}.{t}'
+    if shorten:
+        fmt = '{H}:{M:02}:{S:02}'
+        if totaltime < 3600:
+            fmt = '{M}:{S:02}'
+
+    remainder = int(totaltime)
+    tenths = totaltime-remainder
+
+    f = Formatter()
+    desired_fields = [field_tuple[1] for field_tuple in f.parse(fmt)]
+
+    possible_fields = ('D','H', 'M', 'S')
+    constants = {'D':86400, 'H': 3600, 'M': 60, 'S': 1}
+    values = {}
+    for field in possible_fields:
+        if field in desired_fields and field in constants:
+            values[field], remainder = divmod(remainder, constants[field])
+
+    values['t'] = round(10*tenths)
+
+    return f.format(fmt, **values)
+
+
+def totaltime_sec_to_string_old(totaltime, shorten=False):
     if np.isnan(totaltime):
         return ''
     hours = int(totaltime / 3600.)
     if hours > 23:  # pragma: no cover
         message = 'Warning: The workout duration was longer than 23 hours. '
         hours = 23
+    elif hours < 0:
+        message = 'Warning: invalid workout duration'
+        hours = 0
 
     minutes = int((totaltime - 3600. * hours) / 60.)
     if minutes > 59:  # pragma: no cover
         minutes = 59
         if not message:  # pragma: no cover
             message = 'Warning: there is something wrong with the workout duration'
+    elif minutes < 0:
+        minutes = 0
+        if not message:
+            message = 'Warning: invalid workout duration'
 
     seconds = int(totaltime - 3600. * hours - 60. * minutes)
     if seconds > 59:  # pragma: no cover
         seconds = 59
         if not message:  # pragma: no cover
             message = 'Warning: there is something wrong with the workout duration'
+    elif seconds < 0:
+        seconds = 0
+        if not message:
+            message = 'Warning: invalid workout duration'
 
-    tenths = int(10 * (totaltime - 3600. * hours - 60. * minutes - seconds))
+
+    tenths = round(10 * (totaltime - 3600. * hours - 60. * minutes - seconds))
     if tenths > 9:  # pragma: no cover
         tenths = 9
         if not message:  # pragma: no cover
             message = 'Warning: there is something wrong with the workout duration'
+    elif tenths < 0:
+        tenths = 0
+        if not message:
+            message = 'Warning: invalid workout duration'
 
     duration = ""
     if not shorten: