diff --git a/src/libCom/calc/calcPerform.c b/src/libCom/calc/calcPerform.c
index e53d860e2..b9b28dd3a 100644
--- a/src/libCom/calc/calcPerform.c
+++ b/src/libCom/calc/calcPerform.c
@@ -155,7 +155,7 @@ epicsShareFunc long
 	    break;
 
 	case ABS_VAL:
-	    if (*ptop < 0.0) *ptop = - *ptop;
+	    *ptop = fabs(*ptop);
 	    break;
 
 	case EXP: