diff --git a/tools/perf/util/include/linux/bitops.h b/tools/perf/util/include/linux/bitops.h
index a55d8cf..45cf10a 100644
--- a/tools/perf/util/include/linux/bitops.h
+++ b/tools/perf/util/include/linux/bitops.h
@@ -14,6 +14,7 @@
 #define BITS_TO_LONGS(nr)       DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
 #define BITS_TO_U64(nr)         DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(u64))
 #define BITS_TO_U32(nr)         DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(u32))
+#define BITS_TO_BYTES(nr)       DIV_ROUND_UP(nr, BITS_PER_BYTE)
 
 #define for_each_set_bit(bit, addr, size) \
 	for ((bit) = find_first_bit((addr), (size));		\
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 9bdc60c..b93ff14 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -548,7 +548,7 @@ void perf_pmu__set_format(unsigned long *bits, long from, long to)
 	if (!to)
 		to = from;
 
-	memset(bits, 0, BITS_TO_LONGS(PERF_PMU_FORMAT_BITS));
+	memset(bits, 0, BITS_TO_BYTES(PERF_PMU_FORMAT_BITS));
 	for (b = from; b <= to; b++)
 		set_bit(b, bits);
 }