diff --git a/requirements.txt b/requirements.txt
index d2adddc..e960aef 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,4 +6,3 @@ python-subunit>=0.0.18
 six>=1.5.2
 SQLAlchemy>=0.7.8
 pandas
-numpy
diff --git a/subunit2sql/migrations/versions/5332fe255095_populate_run_time_for_existing_tests.py b/subunit2sql/migrations/versions/5332fe255095_populate_run_time_for_existing_tests.py
index 8ba1578..8d455e6 100644
--- a/subunit2sql/migrations/versions/5332fe255095_populate_run_time_for_existing_tests.py
+++ b/subunit2sql/migrations/versions/5332fe255095_populate_run_time_for_existing_tests.py
@@ -25,7 +25,6 @@ revision = '5332fe255095'
 down_revision = '28ac1ba9c3db'
 
 
-import numpy as np
 from oslo.db.sqlalchemy import utils as db_utils
 
 from subunit2sql.db import api as db_api
@@ -51,7 +50,7 @@ def upgrade():
             results[test_run[0]] = [delta]
 
     for test in results:
-        avg = np.mean(results[test])
+        avg = float(sum(results[test])) / float(len(results[test]))
         db_api.update_test({'run_time': avg}, test)