diff --git a/bag_tools/scripts/bag_add_time_offset.py b/bag_tools/scripts/bag_add_time_offset.py
index 0274998..7ecaf66 100755
--- a/bag_tools/scripts/bag_add_time_offset.py
+++ b/bag_tools/scripts/bag_add_time_offset.py
@@ -62,7 +62,7 @@ def fix_bagfile(inbag, outbag, topics, offset):
     rospy.loginfo('Closing output bagfile.')
     outbag.close()
     rospy.loginfo('Changed the following:')
-    for k, v in count.iteritems():
+    for k, v in count.items():
       rospy.loginfo( '%s:%s messages.',k,v)
 
 if __name__ == "__main__":
@@ -70,13 +70,13 @@ def fix_bagfile(inbag, outbag, topics, offset):
   parser = argparse.ArgumentParser(
       description='Shift the publishing time of given topics in input bagfile.')
   parser.add_argument('-o', metavar='OUTPUT_BAGFILE', required=True, help='output bagfile')
-  parser.add_argument('-i', metavar='INPUT_BAGFILE', required=True, help='input bagfile(s)', nargs='+')
+  parser.add_argument('-i', metavar='INPUT_BAGFILE', required=True, help='input bagfile(s)')
   parser.add_argument('-of', metavar='OFFSET', required=True, type=float, help='time offset to add in seconds')
   parser.add_argument('-t', metavar='TOPIC', required=True, help='topic(s) to change', nargs='+')
   args = parser.parse_args()
   try:
     for bagfile in args.i:
       fix_bagfile(bagfile, args.o, args.t, args.of)
-  except Exception, e:
-      import traceback
-      traceback.print_exc()
+  except Exception as e:
+    import traceback
+    traceback.print_exc()
diff --git a/bag_tools/scripts/check_delay.py b/bag_tools/scripts/check_delay.py
index 93704c3..8093efc 100755
--- a/bag_tools/scripts/check_delay.py
+++ b/bag_tools/scripts/check_delay.py
@@ -38,6 +38,7 @@
 import os
 import sys
 import argparse
+import statistics
 
 def check_delay(inbags):
   delays = {}
@@ -59,12 +60,12 @@ def check_delay(inbags):
         delays[key].append(delay)
   max_len = max(len(topic) for topic in delays.keys())
   topics = delays.keys()
-  topics.sort()
+  list(topics).sort()
   for topic in topics:
     delay_list = delays[topic]
     delay_list.sort()
     dmin, dmax, dmean = min(delay_list), max(delay_list), sum(delay_list)/len(delay_list)
-    dmedian = delay_list[len(delay_list)/2]
+    dmedian = statistics.median(delay_list)
     rospy.loginfo('%s : mean = %s, min = %s, max = %s, median = %s', topic.ljust(max_len + 2), dmean, dmin, dmax, dmedian)
 
 if __name__ == "__main__":
@@ -77,6 +78,6 @@ def check_delay(inbags):
   args = parser.parse_args()
   try:
     check_delay(args.inbag)
-  except Exception, e:
+  except Exception as e:
     import traceback
     traceback.print_exc()