Index: monitoring-plugins-2.3.1/plugins/check_ntp_time.c
===================================================================
--- monitoring-plugins-2.3.1.orig/plugins/check_ntp_time.c
+++ monitoring-plugins-2.3.1/plugins/check_ntp_time.c
@@ -533,7 +533,7 @@ int process_arguments(int argc, char **a
 
 char *perfd_offset (double offset)
 {
-	return fperfdata ("offset", offset, "s",
+	return fperfdata ("offset", fabs(offset), "s",
 		TRUE, offset_thresholds->warning->end,
 		TRUE, offset_thresholds->critical->end,
 		FALSE, 0, FALSE, 0);