diff --git a/garminexport/backup.py b/garminexport/backup.py
index a201140..1d0f11b 100644
--- a/garminexport/backup.py
+++ b/garminexport/backup.py
@@ -45,10 +45,11 @@ def export_filename(activity, export_format):
     :return: The file name to use for the exported activity.
     :rtype: str
     """
-    return "{time}_{id}{suffix}".format(
+    fn = "{time}_{id}{suffix}".format(
         id=activity[0],
         time=activity[1].isoformat(), 
         suffix=format_suffix[export_format])   
+    return fn.replace(':','_') if os.name=='nt' else fn
 
 
 def need_backup(activities, backup_dir, export_formats=None):
diff --git a/garminexport/garminclient.py b/garminexport/garminclient.py
index a443a22..954845f 100755
--- a/garminexport/garminclient.py
+++ b/garminexport/garminclient.py
@@ -12,7 +12,9 @@ from StringIO import StringIO
 import sys
 import zipfile
 import dateutil
+import dateutil.parser
 import os.path
+from functools import wraps
 
 #
 # Note: For more detailed information about the API services
@@ -39,6 +41,7 @@ def require_session(client_function):
     """Decorator that is used to annotate :class:`GarminClient`
     methods that need an authenticated session before being called.
     """
+    @wraps(client_function)
     def check_session(*args, **kwargs):
         client_object = args[0]
         if not client_object.session:
@@ -270,6 +273,7 @@ class GarminClient(object):
         return response.text
 
 
+    @require_session
     def get_activity_tcx(self, activity_id):
         """Return a TCX (Training Center XML) representation of a
         given activity. If the activity doesn't have a TCX source (for
diff --git a/get_activity.py b/get_activity.py
index 94f2f59..3657148 100755
--- a/get_activity.py
+++ b/get_activity.py
@@ -5,11 +5,12 @@ Connect account and stores it locally on the user's computer.
 import argparse
 import getpass
 from garminexport.garminclient import GarminClient
-import garminexport.util
+import garminexport.backup
 import logging
 import os
 import sys
 import traceback
+import dateutil.parser
 
 logging.basicConfig(
     level=logging.INFO, format="%(asctime)-15s [%(levelname)s] %(message)s")
@@ -36,7 +37,7 @@ if __name__ == "__main__":
     parser.add_argument(
         "format", metavar="<format>", type=str,
         help="Export format (one of: {}).".format(
-            garminexport.util.export_formats))
+            garminexport.backup.export_formats))
 
     # optional args
     parser.add_argument(
@@ -54,10 +55,10 @@ if __name__ == "__main__":
     if not args.log_level in LOG_LEVELS:
         raise ValueError("Illegal log-level argument: {}".format(
             args.log_level))
-    if not args.format in garminexport.util.export_formats:
+    if not args.format in garminexport.backup.export_formats:
         raise ValueError(
             "Uncrecognized export format: '{}'. Must be one of {}".format(
-                args.format, garminexport.util.export_formats))
+                args.format, garminexport.backup.export_formats))
     logging.root.setLevel(LOG_LEVELS[args.log_level])
         
     try:
@@ -68,8 +69,10 @@ if __name__ == "__main__":
             args.password = getpass.getpass("Enter password: ")
         with GarminClient(args.username, args.password) as client:
             log.info("fetching activity {} ...".format(args.activity))
-            garminexport.util.export_activity(
-                client, args.activity, args.destination, formats=[args.format])
+            summary = client.get_activity_summary(args.activity)
+            starttime = dateutil.parser.parse(summary["activity"]["activitySummary"]["BeginTimestamp"]["value"])
+            garminexport.backup.download(
+                client, (args.activity, starttime), args.destination, export_formats=[args.format])
     except Exception as e:
         exc_type, exc_value, exc_traceback = sys.exc_info()
         log.error(u"failed with exception: %s", e)
diff --git a/upload_activity.py b/upload_activity.py
old mode 100644
new mode 100755