Index: firmware/App/Modes/ModeTreatmentParams.c
===================================================================
diff -u -r0f11f6c0773aebad3f3a647bdc294f8cca357799 -rdab84d4ac15ba54bb02784c5e359cdc527e9ed05
--- firmware/App/Modes/ModeTreatmentParams.c	(.../ModeTreatmentParams.c)	(revision 0f11f6c0773aebad3f3a647bdc294f8cca357799)
+++ firmware/App/Modes/ModeTreatmentParams.c	(.../ModeTreatmentParams.c)	(revision dab84d4ac15ba54bb02784c5e359cdc527e9ed05)
@@ -38,6 +38,8 @@
 
 #define MAX_DIALYSATE_VOLUME_ML                 ( 150 * ML_PER_LITER )  ///< Maximum dialysate volume (in mL)
 
+#define NO_HEPARIN_PRE_STOP_TIME_SET            0                       ///< Zero value indicates no Heparin pre-stop time was set by user
+
 /// Record for range and default of treatment parameters.
 typedef struct
 {
@@ -571,7 +573,7 @@
     }
 
     // Check Heparin pre-stop vs. no Heparin delivery
-    if ( ( stagedParams[ TREATMENT_PARAM_HEPARIN_PRE_STOP_TIME ].uInt > 0 ) &&
+    if ( ( stagedParams[ TREATMENT_PARAM_HEPARIN_PRE_STOP_TIME ].uInt > NO_HEPARIN_PRE_STOP_TIME_SET ) &&
          ( stagedParams[ TREATMENT_PARAM_HEPARIN_DISPENSE_RATE ].sFlt < NEARLY_ZERO ) &&
          ( stagedParams[ TREATMENT_PARAM_HEPARIN_BOLUS_VOLUME ].sFlt < NEARLY_ZERO ) )
     {