diff --git a/solanaceae/util/bitset.hpp b/solanaceae/util/bitset.hpp
index 1b04727..43642be 100644
--- a/solanaceae/util/bitset.hpp
+++ b/solanaceae/util/bitset.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <cstdint>
+#include <cstddef>
 #include <vector>