diff --git a/drivers/net/dm9000.c b/drivers/net/dm9000.c
index bcf9291..254ec62 100644
--- a/drivers/net/dm9000.c
+++ b/drivers/net/dm9000.c
@@ -930,13 +930,15 @@
 	struct net_device *dev = dev_id;
 	board_info_t *db = netdev_priv(dev);
 	int int_status;
+	unsigned long flags;
 	u8 reg_save;
 
 	dm9000_dbg(db, 3, "entering %s\n", __func__);
 
 	/* A real interrupt coming */
 
-	spin_lock(&db->lock);
+	/* holders of db->lock must always block IRQs */
+	spin_lock_irqsave(&db->lock, flags);
 
 	/* Save previous register address */
 	reg_save = readb(db->io_addr);
@@ -972,7 +974,7 @@
 	/* Restore previous register address */
 	writeb(reg_save, db->io_addr);
 
-	spin_unlock(&db->lock);
+	spin_unlock_irqrestore(&db->lock, flags);
 
 	return IRQ_HANDLED;
 }