diff --git a/lms/djangoapps/grades/management/commands/reset_grades.py b/lms/djangoapps/grades/management/commands/reset_grades.py
index 8d6d95ca92..811ffbda8e 100644
--- a/lms/djangoapps/grades/management/commands/reset_grades.py
+++ b/lms/djangoapps/grades/management/commands/reset_grades.py
@@ -3,6 +3,7 @@ Reset persistent grades for learners.
 """
 from datetime import datetime
 import logging
+from pytz import utc
 from textwrap import dedent
 
 from django.core.management.base import BaseCommand, CommandError
@@ -58,12 +59,12 @@ class Command(BaseCommand):
         parser.add_argument(
             '--modified_start',
             dest='modified_start',
-            help='Starting range for modified date (inclusive): e.g. "2016-08-23 16:43"',
+            help='Starting range for modified date (inclusive): e.g. "2016-08-23 16:43"; expected in UTC.',
         )
         parser.add_argument(
             '--modified_end',
             dest='modified_end',
-            help='Ending range for modified date (inclusive): e.g. "2016-12-23 16:43"',
+            help='Ending range for modified date (inclusive): e.g. "2016-12-23 16:43"; expected in UTC.',
         )
         parser.add_argument(
             '--db_table',
@@ -84,12 +85,12 @@ class Command(BaseCommand):
             raise CommandError('Invalid value for db_table. Valid options are "subsection" or "course" only.')
 
         if options.get('modified_start'):
-            modified_start = datetime.strptime(options['modified_start'], DATE_FORMAT)
+            modified_start = utc.localize(datetime.strptime(options['modified_start'], DATE_FORMAT))
 
         if options.get('modified_end'):
             if not modified_start:
                 raise CommandError('Optional value for modified_end provided without a value for modified_start.')
-            modified_end = datetime.strptime(options['modified_end'], DATE_FORMAT)
+            modified_end = utc.localize(datetime.strptime(options['modified_end'], DATE_FORMAT))
 
         if courses_mode == 'courses':
             course_keys = parse_course_keys(options['courses'])