diff --git a/src/base/net/tools/MemPool.h b/src/base/net/tools/MemPool.h
index e7cf3a19a..8a0a126b4 100644
--- a/src/base/net/tools/MemPool.h
+++ b/src/base/net/tools/MemPool.h
@@ -22,6 +22,7 @@
 
 #include <array>
 #include <cassert>
+#include <cstddef>
 #include <map>
 #include <set>