diff --git a/sys/boot/i386/kgzldr/Makefile b/sys/boot/i386/kgzldr/Makefile
index ea4e70174d20..2a4513d4b568 100644
--- a/sys/boot/i386/kgzldr/Makefile
+++ b/sys/boot/i386/kgzldr/Makefile
@@ -4,7 +4,12 @@ MAINTAINER=	rnordier
 
 PROG=	kgzldr.o
 SRCS=	start.s boot.c inflate.c lib.c crt.s sio.s
-CFLAGS=	-fno-builtin -Os
+CFLAGS=	-fno-builtin
+.if ${OBJFORMAT} == aout
+CFLAGS+=-O2
+.else
+CFLAGS+=-Os
+.endif
 CFLAGS+=-DKZIP
 LDFLAGS=-nostdlib -static -r
 NOMAN=
@@ -14,7 +19,7 @@ STRIP=
 .PATH:	${.CURDIR}/../../../kern
 
 M4?=	m4
-M4FLAGS=
+M4FLAGS=-DOBJFORMAT=${OBJFORMAT}
 
 BOOT_COMCONSOLE_PORT?=	0x3f8
 M4FLAGS+=-DSIOPRT=${BOOT_COMCONSOLE_PORT}
@@ -25,7 +30,7 @@ kgzldr.o: ${OBJS}
 	${CC} ${LDFLAGS} -o ${.TARGET} ${OBJS}
 
 .s.o:
-	(cd ${.CURDIR}; ${M4} ${M4FLAGS} ${.IMPSRC}) |\
+	(cd ${.CURDIR}; ${M4} ${M4FLAGS} kgzldr.m4 ${.IMPSRC}) |\
 		${AS} ${AFLAGS} -o ${.TARGET}
 
 .include <bsd.prog.mk>
diff --git a/sys/boot/i386/kgzldr/crt.s b/sys/boot/i386/kgzldr/crt.s
index cfb479fd2d84..ac26a20409ed 100644
--- a/sys/boot/i386/kgzldr/crt.s
+++ b/sys/boot/i386/kgzldr/crt.s
@@ -38,11 +38,11 @@
 		.set BDA_SCR,0x449		# Video mode
 		.set BDA_POS,0x450		# Cursor position
 
-		.globl crt_putchr
+		.globl _(crt_putchr)
 
 # void crt_putchr(int c)
 
-crt_putchr: 	movb 0x4(%esp,1),%al		# Get character
+_(crt_putchr): 	movb 0x4(%esp,1),%al		# Get character
 		pusha				# Save
 		xorl %ecx,%ecx			# Zero for loops
 		movb $SCR_MAT,%ah		# Mode/attribute
diff --git a/sys/boot/i386/kgzldr/kgzldr.m4 b/sys/boot/i386/kgzldr/kgzldr.m4
new file mode 100644
index 000000000000..1441a4b4a01c
--- /dev/null
+++ b/sys/boot/i386/kgzldr/kgzldr.m4
@@ -0,0 +1,18 @@
+#
+# Copyright (c) 2000 Robert Nordier
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms are freely
+# permitted provided that the above copyright notice and this
+# paragraph and the following disclaimer are duplicated in all
+# such forms.
+#
+# This software is provided "AS IS" and without any express or
+# implied warranties, including, without limitation, the implied
+# warranties of merchantability and fitness for a particular
+# purpose.
+#
+
+# $FreeBSD$
+
+define(_,`ifelse(OBJFORMAT,`aout',`_$1',`$1')')
diff --git a/sys/boot/i386/kgzldr/sio.s b/sys/boot/i386/kgzldr/sio.s
index bb354e297dd0..86b8ccd1d1a4 100644
--- a/sys/boot/i386/kgzldr/sio.s
+++ b/sys/boot/i386/kgzldr/sio.s
@@ -29,18 +29,18 @@
 
 		.set SIO_PRT,SIOPRT		# Base port
 
-		.globl sio_putchr
+		.globl _(sio_putchr)
 
 # void sio_putchr(int c)
 
-sio_putchr:	movw $SIO_PRT+0x5,%dx		# Line status reg
+_(sio_putchr):	movw $SIO_PRT+0x5,%dx		# Line status reg
 		xor %ecx,%ecx			# Timeout
 		movb $0x40,%ch			#  counter
-sio_putchr.1:	inb (%dx),%al			# Transmitter
+sio_putchr.1:	inb %dx,%al			# Transmitter
 		testb $0x20,%al 		#  buffer empty?
 		loopz sio_putchr.1		# No
 		jz sio_putchr.2			# If timeout
 		movb 0x4(%esp,1),%al		# Get character
 		subb $0x5,%dl			# Transmitter hold reg
-		outb %al,(%dx)			# Write character
+		outb %al,%dx			# Write character
 sio_putchr.2:	ret				# To caller
diff --git a/sys/boot/i386/kgzldr/start.s b/sys/boot/i386/kgzldr/start.s
index 550fa526d946..ff43c77b3f2e 100644
--- a/sys/boot/i386/kgzldr/start.s
+++ b/sys/boot/i386/kgzldr/start.s
@@ -40,6 +40,6 @@ _start:		cld				# String ops inc
 		rep				# Clear
 		stosb				#  bss
 		pushl 0x4(%esp)			# Pass howto flags
-		call boot			# Call C code
+		call _(boot)			# Call C code
 		popl %ecx			# Clear stack
-		jmp *kgz+entry			# To loaded code
+		jmp *_(kgz)+entry		# To loaded code