Index: firmware/App/Services/Reservoirs.c
===================================================================
diff -u -r11c4c22fd07359724a2b2e5633e9d795b913c0b0 -rb663723e1e35b02546ea1d8ad310cf5db18376a6
--- firmware/App/Services/Reservoirs.c	(.../Reservoirs.c)	(revision 11c4c22fd07359724a2b2e5633e9d795b913c0b0)
+++ firmware/App/Services/Reservoirs.c	(.../Reservoirs.c)	(revision b663723e1e35b02546ea1d8ad310cf5db18376a6)
@@ -324,7 +324,7 @@
     {
         // fill flow = linear interpolation between 350 MLP and 550MLP
         fillFlowRate = TGT_FILL_FLOW_FOR_DIA_FLOW_100_TO_350_ML_PER_MIN
-                       + ( ( dialysateFlow - DIALYSATE_FLOW_RATE_350_ML_PER_MIN ) / (DIALYSATE_FLOW_RATE_550_ML_PER_MIN - dialysateFlow ) )
+                       + ( ( dialysateFlow - DIALYSATE_FLOW_RATE_350_ML_PER_MIN ) / (DIALYSATE_FLOW_RATE_550_ML_PER_MIN - DIALYSATE_FLOW_RATE_350_ML_PER_MIN ) )
                        * ( TGT_FILL_FLOW_FOR_DIA_FLOW_550_TO_600_ML_PER_MIN - TGT_FILL_FLOW_FOR_DIA_FLOW_100_TO_350_ML_PER_MIN );
     }