--- serial.c.orig	Tue Nov 13 20:50:16 2001
+++ serial.c	Tue Nov 13 20:52:28 2001
@@ -2077,6 +2077,7 @@
 	unsigned int		i,change_irq,change_port;
 	int 			retval = 0;
 	unsigned long		new_port;
+	unsigned long           new_mem;
 
 	if (copy_from_user(&new_serial,new_info,sizeof(new_serial)))
 		return -EFAULT;
@@ -2087,6 +2088,8 @@
 	if (HIGH_BITS_OFFSET)
 		new_port += (unsigned long) new_serial.port_high << HIGH_BITS_OFFSET;
 
+	new_mem = new_serial.iomem_base;
+
 	change_irq = new_serial.irq != state->irq;
 	change_port = (new_port != ((int) state->port)) ||
 		(new_serial.hub6 != state->hub6);
@@ -2127,6 +2130,7 @@
 		for (i = 0 ; i < NR_PORTS; i++)
 			if ((state != &rs_table[i]) &&
 			    (rs_table[i].port == new_port) &&
+			    (rs_table[i].iomem_base == new_mem) &&
 			    rs_table[i].type)
 				return -EADDRINUSE;
 	}