diff --git a/openquake/calculators/base.py b/openquake/calculators/base.py
index <HASH>..<HASH> 100644
--- a/openquake/calculators/base.py
+++ b/openquake/calculators/base.py
@@ -16,7 +16,6 @@
 #  You should have received a copy of the GNU Affero General Public License
 #  along with OpenQuake.  If not, see <http://www.gnu.org/licenses/>.
 
-import os
 import sys
 import abc
 import pdb
diff --git a/openquake/calculators/event_based_risk.py b/openquake/calculators/event_based_risk.py
index <HASH>..<HASH> 100644
--- a/openquake/calculators/event_based_risk.py
+++ b/openquake/calculators/event_based_risk.py
@@ -23,7 +23,7 @@ import collections
 import numpy
 
 from openquake.baselib.general import AccumDict, humansize
-from openquake.calculators import base
+from openquake.calculators import base, event_based
 from openquake.commonlib import readinput, parallel, datastore
 from openquake.risklib import riskinput, scientific
 from openquake.commonlib.parallel import apply_reduce
@@ -151,7 +151,7 @@ class EventBasedRiskCalculator(base.RiskCalculator):
     Event based PSHA calculator generating the event loss table and
     fixed ratios loss curves.
     """
-    pre_calculator = 'event_based_rupture'
+    pre_calculator = 'event_based'
     core_func = event_based_risk
 
     epsilon_matrix = datastore.persistent_attribute('epsilon_matrix')
Fixed EventBasedRiskCalculator.pre_calculator