diff --git a/sys/modules/cam/Makefile b/sys/modules/cam/Makefile
index ff90f8138240..055ec2a34313 100644
--- a/sys/modules/cam/Makefile
+++ b/sys/modules/cam/Makefile
@@ -7,6 +7,10 @@ S=	${.CURDIR}/../..
 
 KMOD=	cam
 
+.if ${MACHINE} == "pc98"
+CFLAGS+= -DPC98
+.endif
+
 # See sys/conf/options for the flags that go into the different opt_*.h files.
 SRCS=	opt_cam.h
 SRCS+=	opt_scsi.h