diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
index dc5c5e6fc502d55903323b54be14a2658d7869d5..20e3a75953fce413b87b19235309e764e9b743e5 100644
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -132,15 +132,16 @@ int cpu_map__build_map(struct perf_cpu_map *cpus, struct perf_cpu_map **res,
 		       int (*f)(struct perf_cpu_map *map, int cpu, void *data),
 		       void *data)
 {
-	struct perf_cpu_map *c;
 	int nr = cpus->nr;
+	struct perf_cpu_map *c = perf_cpu_map__empty_new(nr);
 	int cpu, s1, s2;
 
-	/* allocate as much as possible */
-	c = calloc(1, sizeof(*c) + nr * sizeof(int));
 	if (!c)
 		return -1;
 
+	/* Reset size as it may only be partially filled */
+	c->nr = 0;
+
 	for (cpu = 0; cpu < nr; cpu++) {
 		s1 = f(cpus, cpu, data);
 		for (s2 = 0; s2 < c->nr; s2++) {
@@ -155,7 +156,6 @@ int cpu_map__build_map(struct perf_cpu_map *cpus, struct perf_cpu_map **res,
 	/* ensure we process id in increasing order */
 	qsort(c->map, c->nr, sizeof(int), cmp_ids);
 
-	refcount_set(&c->refcnt, 1);
 	*res = c;
 	return 0;
 }