diff --git a/sys/arch/i386/stand/efiboot/bootx64/Makefile b/sys/arch/i386/stand/efiboot/bootx64/Makefile
index 904f7463edb4..8220c4f5dc3c 100644
--- a/sys/arch/i386/stand/efiboot/bootx64/Makefile
+++ b/sys/arch/i386/stand/efiboot/bootx64/Makefile
@@ -1,4 +1,4 @@
-#	$NetBSD: Makefile,v 1.2 2019/09/13 02:19:46 manu Exp $
+#	$NetBSD: Makefile,v 1.3 2020/03/21 18:43:47 riastradh Exp $
 
 PROG=		bootx64.efi
 OBJFMT=		pei-x86-64
@@ -9,4 +9,9 @@ EXTRA_SOURCES=	efibootx64.c startprog64.S multiboot64.S
 COPTS+=		-mno-red-zone
 CPPFLAGS+=	-DEFI_FUNCTION_WRAPPER
 
+# Follow the suit of Makefile.kern.inc; needed for the lfs64 union
+# accessors -- they don't actually dereference the resulting pointer,
+# just use it for type-checking.
+CWARNFLAGS.clang+=	-Wno-error=address-of-packed-member
+
 .include "${.CURDIR}/../Makefile.efiboot"