diff --git a/libc/private/bsd_sys_param.h b/libc/private/bsd_sys_param.h
index be5f692..ab54aa0 100644
--- a/libc/private/bsd_sys_param.h
+++ b/libc/private/bsd_sys_param.h
@@ -20,4 +20,4 @@
 
 /* OpenBSD has these in <sys/param.h>, but "ALIGN" isn't something we want to reserve. */
 #define ALIGNBYTES (sizeof(uintptr_t) - 1)
-#define ALIGN(p) (((uintptr_t)(p) + ALIGNBYTES) & ~ALIGNBYTES)
+#define ALIGN(p) ((__BIONIC_CAST(reinterpret_cast, uintptr_t, p) + ALIGNBYTES) & ~ALIGNBYTES)