Index: firmware/App/Modes/Dialysis.c
===================================================================
diff -u -rc84daa1f07003427fc5cdde8f5651434478f7313 -re28798081348b470495ec605fcadda4276f37c46
--- firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision c84daa1f07003427fc5cdde8f5651434478f7313)
+++ firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision e28798081348b470495ec605fcadda4276f37c46)
@@ -15,6 +15,8 @@
 *
 ***************************************************************************/
 
+#include <math.h>
+
 #include "BloodFlow.h"
 #include "Buttons.h"
 #include "DGInterface.h"
@@ -589,7 +591,7 @@
     }
 
     // check total UF volume error
-    if ( ( FABS( refUFVolume - measUFVolume ) ) >= (F32)MAX_UF_ACCURACY_ERROR_ML )
+    if ( ( fabs( refUFVolume - measUFVolume ) ) >= (F32)MAX_UF_ACCURACY_ERROR_ML )
     {
 #ifndef DISABLE_UF_ALARMS
         SET_ALARM_WITH_2_F32_DATA( ALARM_ID_UF_VOLUME_ACCURACY_ERROR, refUFVolume, measUFVolume );