Index: firmware/App/Controllers/BloodFlow.c
===================================================================
diff -u -r1ebbe403d260d9f65695c13d6dbafbe1a93cfdde -r651dcf74b57105a1247d1a29a4e9df2bd8d56649
--- firmware/App/Controllers/BloodFlow.c	(.../BloodFlow.c)	(revision 1ebbe403d260d9f65695c13d6dbafbe1a93cfdde)
+++ firmware/App/Controllers/BloodFlow.c	(.../BloodFlow.c)	(revision 651dcf74b57105a1247d1a29a4e9df2bd8d56649)
@@ -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;