Index: firmware/App/Modes/ModeTreatment.c
===================================================================
diff -u -rf3ecaf3a7bc6d07225791f43196c468ff05ad016 -red2a4cf95e008d002016dd40d7bb79efc135ad36
--- firmware/App/Modes/ModeTreatment.c	(.../ModeTreatment.c)	(revision f3ecaf3a7bc6d07225791f43196c468ff05ad016)
+++ firmware/App/Modes/ModeTreatment.c	(.../ModeTreatment.c)	(revision ed2a4cf95e008d002016dd40d7bb79efc135ad36)
@@ -1059,8 +1059,9 @@
         // Always keep the UF volume the same and change the UF rate upon changing the treatment time
         presMaxUFVolumeML = getTreatmentParameterF32( TREATMENT_PARAM_UF_VOLUME ) * (F32)ML_PER_LITER;
 
+        F32 newUFDiffML       = ( ( presMaxUFVolumeML - getTotalMeasuredUFVolumeInMl() ) < 0.0F ? 0.0F : ( presMaxUFVolumeML - getTotalMeasuredUFVolumeInMl() ) );
         // New UF rate is how much UF is left to be done / remaining treatment time
-        F32 newUFRateMLPM     = ( presMaxUFVolumeML - getTotalMeasuredUFVolumeInMl() ) / (F32)( treatmentTime - CALC_ELAPSED_TREAT_TIME_IN_MIN() );
+        F32 newUFRateMLPM     = ( newUFDiffML ) / (F32)( treatmentTime - CALC_ELAPSED_TREAT_TIME_IN_MIN() );
         U32 dialVolume        = getTreatmentParameterU32( TREATMENT_PARAM_DIALYSATE_FLOW ) * treatmentTime;   // In mL
 
         // The minimum treatment time is either in the range of the institutional record or the 1-minute treatment config has been requested which is an exception