diff --git a/sys/boot/i386/btx/btx/Makefile b/sys/boot/i386/btx/btx/Makefile
index 9784aed..236d269 100644
--- a/sys/boot/i386/btx/btx/Makefile
+++ b/sys/boot/i386/btx/btx/Makefile
@@ -11,7 +11,7 @@ BOOT_BTX_FLAGS=0x1
 BOOT_BTX_FLAGS=0x0
 .endif
 
-CFLAGS+=-DBTX_FLAGS=${BOOT_BTX_FLAGS} -DLOCORE
+CFLAGS+=-DBTX_FLAGS=${BOOT_BTX_FLAGS}
 CFLAGS+=-I${.CURDIR}/../../common
 
 .if defined(BTX_SERIAL)
diff --git a/sys/boot/i386/btx/btxldr/Makefile b/sys/boot/i386/btx/btxldr/Makefile
index 7378e92..b76468b 100644
--- a/sys/boot/i386/btx/btxldr/Makefile
+++ b/sys/boot/i386/btx/btxldr/Makefile
@@ -5,7 +5,7 @@ INTERNALPROG=
 NO_MAN=
 SRCS=	btxldr.S
 
-CFLAGS+=-DLOADER_ADDRESS=${LOADER_ADDRESS} -DLOCORE
+CFLAGS+=-DLOADER_ADDRESS=${LOADER_ADDRESS}
 CFLAGS+=-I${.CURDIR}/../../common
 
 .if defined(BTXLDR_VERBOSE)
diff --git a/sys/boot/i386/btx/btxldr/btxldr.S b/sys/boot/i386/btx/btxldr/btxldr.S
index 4d00d61..3a58210 100644
--- a/sys/boot/i386/btx/btxldr/btxldr.S
+++ b/sys/boot/i386/btx/btxldr/btxldr.S
@@ -103,7 +103,7 @@ start.1:	movl (%ebx),%eax		# Get argument and
 		movl BI_OFF+4(%esp),%esi	# Source: bootinfo
 		cmpl $0x0, %esi			# If the bootinfo pointer
 		je start_null_bi		#  is null, don't copy it
-		movl $BI_SIZE,%ecx 		# Allocate space
+		movl BI_SIZE(%esi),%ecx 	# Allocate space
 		subl %ecx,%ebp			#  for bootinfo
 		movl %ebp,%edi			# Destination
 		rep				# Copy
diff --git a/sys/boot/i386/btx/lib/Makefile b/sys/boot/i386/btx/lib/Makefile
index 08c04d8..856d868 100644
--- a/sys/boot/i386/btx/lib/Makefile
+++ b/sys/boot/i386/btx/lib/Makefile
@@ -4,7 +4,6 @@ PROG=	crt0.o
 INTERNALPROG=
 NO_MAN=
 SRCS=	btxcsu.S btxsys.s btxv86.s
-CFLAGS+=-DLOCORE
 CFLAGS+=-I${.CURDIR}/../../common
 LDFLAGS=-Wl,-r
 
diff --git a/sys/boot/i386/common/bootargs.h b/sys/boot/i386/common/bootargs.h
index e90e342..510efdd 100644
--- a/sys/boot/i386/common/bootargs.h
+++ b/sys/boot/i386/common/bootargs.h
@@ -23,17 +23,17 @@
 #define	KARGS_FLAGS_ZFS		0x4
 #define	KARGS_FLAGS_EXTARG	0x8	/* variably sized extended argument */
 
-#define	BI_SIZE			72	/* struct bootinfo fixed size */
-#define	BA_SIZE			24	/* struct bootargs fixed size */
-#define	HT_OFF			0	/* offset of howto in bootargs */
-#define	BF_OFF			8	/* offset of bootflags in bootargs */
-#define	BI_OFF			20	/* offset of bootinfo in bootargs */
+#define	BI_SIZE		48	/* offsetof(struct bootinfo, bi_size) */
+#define	BA_SIZE		24	/* sizeof(struct bootargs) */
+#define	HT_OFF		0	/* offsetof(struct bootargs, howto) */
+#define	BF_OFF		8	/* offsetof(struct bootargs, bootflags) */
+#define	BI_OFF		20	/* offsetof(struct bootargs, bootinfo) */
 
-#define	ARGSPACE		0x1000	/* size of the BTX args area */
-#define	ARGOFF			0x800	/* args offset within the args area */
-#define	ARGADJ			(ARGSPACE - ARGOFF)
+#define	ARGSPACE	0x1000	/* total size of the BTX args area */
+#define	ARGOFF		0x800	/* actual args offset within the args area */
+#define	ARGADJ		(ARGSPACE - ARGOFF)
 
-#ifndef LOCORE
+#ifndef __ASSEMBLER__
 
 struct bootargs
 {
@@ -56,6 +56,6 @@ struct bootargs
 	 */
 };
 
-#endif /*LOCORE*/
+#endif /*__ASSEMBLER__*/
 
 #endif	/* !_BOOT_I386_ARGS_H_ */
diff --git a/sys/boot/i386/loader/main.c b/sys/boot/i386/loader/main.c
index 451b472..f32ece1 100644
--- a/sys/boot/i386/loader/main.c
+++ b/sys/boot/i386/loader/main.c
@@ -48,10 +48,13 @@ __FBSDID("$FreeBSD$");
 #include "../zfs/libzfs.h"
 #endif
 
+CTASSERT(sizeof(struct bootargs) == BA_SIZE);
+CTASSERT(offsetof(struct bootargs, bootinfo) == BI_OFF);
+CTASSERT(offsetof(struct bootargs, bootflags) == BF_OFF);
+CTASSERT(offsetof(struct bootinfo, bi_size) == BI_SIZE);
+
 /* Arguments passed in from the boot1/boot2 loader */
 static struct bootargs *kargs;
-CTASSERT(sizeof(struct bootargs) == BA_SIZE);
-/*CTASSERT(sizeof(struct bootinfo) == BI_SIZE);*//*XXX*/
 
 static u_int32_t	initial_howto;
 static u_int32_t	initial_bootdev;