diff --git a/sys/compat/freebsd32/freebsd32_misc.c b/sys/compat/freebsd32/freebsd32_misc.c
--- a/sys/compat/freebsd32/freebsd32_misc.c
+++ b/sys/compat/freebsd32/freebsd32_misc.c
@@ -4249,10 +4249,14 @@
 	error = copyin(uap->wcred, &wcred32, sizeof(wcred32));
 	if (error != 0)
 		return (error);
-	/* These fields have exactly the same sizes and positions. */
-	memcpy(&wcred, &wcred32, __rangeof(struct setcred32,
-	    setcred32_copy_start, setcred32_copy_end));
-	/* Remaining fields are pointers and need PTRIN*(). */
+	memset(&wcred, 0, sizeof(wcred));
+	CP(wcred32, wcred, sc_uid);
+	CP(wcred32, wcred, sc_ruid);
+	CP(wcred32, wcred, sc_svuid);
+	CP(wcred32, wcred, sc_gid);
+	CP(wcred32, wcred, sc_rgid);
+	CP(wcred32, wcred, sc_svgid);
+	CP(wcred32, wcred, sc_supp_groups_nb);
 	PTRIN_CP(wcred32, wcred, sc_supp_groups);
 	PTRIN_CP(wcred32, wcred, sc_label);
 	return (user_setcred(td, uap->flags, &wcred));
diff --git a/sys/sys/ucred.h b/sys/sys/ucred.h
--- a/sys/sys/ucred.h
+++ b/sys/sys/ucred.h
@@ -181,7 +181,6 @@
     SETCREDF_MAC_LABEL)
 
 struct setcred32 {
-#define	setcred32_copy_start	sc_uid
 	uid_t	 sc_uid;
 	uid_t	 sc_ruid;
 	uid_t	 sc_svuid;
@@ -190,7 +189,6 @@
 	gid_t	 sc_svgid;
 	u_int	 sc_pad;
 	u_int	 sc_supp_groups_nb;
-#define	setcred32_copy_end	sc_supp_groups
 	uint32_t sc_supp_groups;	/* gid_t [*] */
 	uint32_t sc_label;		/* struct mac32 [*] */
 };