diff --git a/zipline/finance/constants.py b/zipline/finance/constants.py
index ce7ec8f6..9dbc6a3c 100644
--- a/zipline/finance/constants.py
+++ b/zipline/finance/constants.py
@@ -14,7 +14,7 @@
 # limitations under the License.
 
 TRADING_DAYS_IN_YEAR = 250
-TRADING_HOURS_IN_DAY = 6
+TRADING_HOURS_IN_DAY = 6.5
 MINUTES_IN_HOUR = 60
 
 ANNUALIZER = {'daily': TRADING_DAYS_IN_YEAR,