Index: firmware/App/Controllers/BloodFlow.c
===================================================================
diff -u -r1c628bfd5d6414b74b8cbd083f66839888a8236b -rd80c4a21ab700d8197e292f34c86dad61828c45a
--- firmware/App/Controllers/BloodFlow.c	(.../BloodFlow.c)	(revision 1c628bfd5d6414b74b8cbd083f66839888a8236b)
+++ firmware/App/Controllers/BloodFlow.c	(.../BloodFlow.c)	(revision d80c4a21ab700d8197e292f34c86dad61828c45a)
@@ -1063,7 +1063,7 @@
 
         // Keep a running 32-bit edge count used for safety check on volume in some functions
         delta = u16BiDiffWithWrap( last, bpMotorHallSensorCount );
-        bloodPumpMotorEdgeCount += (U16)delta;
+        bloodPumpMotorEdgeCount += ( delta >= 0 ? (U16)delta : 0 );
 
         // Update last count for next time
         bpLastMotorHallSensorCounts[ nextIdx ] = bpMotorHallSensorCount;