diff --git a/usr.sbin/bhyve/bhyverun.c b/usr.sbin/bhyve/bhyverun.c
--- a/usr.sbin/bhyve/bhyverun.c
+++ b/usr.sbin/bhyve/bhyverun.c
@@ -1535,8 +1535,13 @@
 		assert(error == 0);
 	}
 
-	if (lpc_bootrom())
-		fwctl_init();
+	if (lpc_bootrom()) {
+		error = fwctl_init();
+		if (error) {
+			perror("bhyve fwctl initialization error");
+			exit(4);
+		}
+	}
 
 	/*
 	 * Change the proc title to include the VM name.
diff --git a/usr.sbin/bhyve/fwctl.h b/usr.sbin/bhyve/fwctl.h
--- a/usr.sbin/bhyve/fwctl.h
+++ b/usr.sbin/bhyve/fwctl.h
@@ -51,6 +51,6 @@
 	};							\
 	DATA_SET(ctl_set, __CONCAT(__ctl, __LINE__))
 
-void	fwctl_init(void);
+int	fwctl_init(void);
 
 #endif /* _FWCTL_H_ */
diff --git a/usr.sbin/bhyve/fwctl.c b/usr.sbin/bhyve/fwctl.c
--- a/usr.sbin/bhyve/fwctl.c
+++ b/usr.sbin/bhyve/fwctl.c
@@ -538,15 +538,39 @@
 
 	return (0);
 }
-INOUT_PORT(fwctl_wreg, FWCTL_OUT, IOPORT_F_INOUT, fwctl_handler);
-INOUT_PORT(fwctl_rreg, FWCTL_IN,  IOPORT_F_IN,    fwctl_handler);
 
-void
+int
 fwctl_init(void)
 {
+	struct inout_port iop;
+	int error;
+
+	bzero(&iop, sizeof(iop));
+	iop.name = "fwctl_wreg";
+	iop.port = FWCTL_OUT;
+	iop.size = 1;
+	iop.flags = IOPORT_F_INOUT;
+	iop.handler = fwctl_handler;
+
+	if ((error = register_inout(&iop)) != 0) {
+		return (error);
+	}
+
+	bzero(&iop, sizeof(iop));
+	iop.name = "fwctl_rreg";
+	iop.port = FWCTL_IN;
+	iop.size = 1;
+	iop.flags = IOPORT_F_IN;
+	iop.handler = fwctl_handler;
+
+	if ((error = register_inout(&iop)) != 0) {
+		return (error);
+	}
 
 	ops[OP_GET_LEN] = &fgetlen_info;
 	ops[OP_GET]     = &fgetval_info;
 
 	be_state = IDENT_WAIT;
+
+	return (0);
 }