diff --git a/libc/platform/bionic/macros.h b/libc/platform/bionic/macros.h
index b2d6f96..1e7ca88 100644
--- a/libc/platform/bionic/macros.h
+++ b/libc/platform/bionic/macros.h
@@ -16,6 +16,7 @@
 
 #pragma once
 
+#include <stddef.h>
 #include <stdint.h>
 
 #define BIONIC_DISALLOW_COPY_AND_ASSIGN(TypeName) \