diff --git a/tools/perf/builtin-timechart.c b/tools/perf/builtin-timechart.c
index 746cf03..0ace786 100644
--- a/tools/perf/builtin-timechart.c
+++ b/tools/perf/builtin-timechart.c
@@ -264,9 +264,6 @@
 		c->start_time = start;
 	if (p->start_time == 0 || p->start_time > start)
 		p->start_time = start;
-
-	if (cpu > numcpus)
-		numcpus = cpu;
 }
 
 #define MAX_CPUS 4096
@@ -511,6 +508,9 @@
 		if (!event_str)
 			return 0;
 
+		if (sample->cpu > numcpus)
+			numcpus = sample->cpu;
+
 		if (strcmp(event_str, "power:cpu_idle") == 0) {
 			struct power_processor_entry *ppe = (void *)te;
 			if (ppe->state == (u32)PWR_EVENT_EXIT)