Index: wflow-py/wflow/wflow_bmi.py
===================================================================
diff -u -r22099d5f96ebe558a76482978ef52ac98e3050a9 -rd8108b35c021a0624372a8ea9537ff97300bffd1
--- wflow-py/wflow/wflow_bmi.py	(.../wflow_bmi.py)	(revision 22099d5f96ebe558a76482978ef52ac98e3050a9)
+++ wflow-py/wflow/wflow_bmi.py	(.../wflow_bmi.py)	(revision d8108b35c021a0624372a8ea9537ff97300bffd1)
@@ -111,17 +111,15 @@
     def update(self, dt):
         """
         Return type string, compatible with numpy.
-        Propagate the model dt timesteps or ( if dt == -1) to the end of the model run
+        Propagate the model dt seconds or ( if dt == -1) one timestep
         """
         # TODO: fix dt = -1 problem, what do we want here?
         #curstep = self.dynModel.wf_
         if dt == -1:
             self.bmilogger.debug("update: dt = " + str(dt))
-            self.bmilogger.debug("update: update until end of run")
-            lasttimestep = (self.get_end_time() - self.get_start_time())/self.dynModel.timestepsecs
-            steptodo = lasttimestep - self.currenttimestep
-            self.dynModel._runDynamic(self.currenttimestep, lasttimestep)
-            self.currenttimestep = self.currenttimestep + steptodo
+            self.bmilogger.debug("update: update default, 1 timestep")
+            self.dynModel._runDynamic(self.currenttimestep, self.currenttimestep)
+            self.currenttimestep = self.currenttimestep + 1
         else:
             nrsteps = int(dt/self.dynModel.timestepsecs)
             self.bmilogger.debug("update: dt = " + str(dt))