diff --git a/sys/sys/_types.h b/sys/sys/_types.h
--- a/sys/sys/_types.h
+++ b/sys/sys/_types.h
@@ -226,6 +226,7 @@
 typedef union {
 	char		__mbstate8[128];
 	__int64_t	_mbstateL;	/* for alignment */
+	__intptr_t	_mbstateP;	/* for alignment */
 } __mbstate_t;
 
 typedef __uintmax_t     __rman_res_t;