diff --git a/libtorrent/src/torrent/bitfield.cc b/libtorrent/src/torrent/bitfield.cc
index 5f29d035..b6c284e5 100644
--- a/libtorrent/src/torrent/bitfield.cc
+++ b/libtorrent/src/torrent/bitfield.cc
@@ -89,7 +89,7 @@ Bitfield::update() {
   clear_tail();
 
   #if USE_AVX2_POPCOUNT
-  m_set = rak::popcnt_AVX2_lookup(m_data, size_bytes());
+  m_set = rak::popcnt_AVX2_lookup(m_data, size_bits());
   #else
   m_set = 0;