diff --git a/drivers/char/stallion.c b/drivers/char/stallion.c
index 7612464..87bda40b 100644
--- a/drivers/char/stallion.c
+++ b/drivers/char/stallion.c
@@ -136,6 +136,7 @@
 
 /*****************************************************************************/
 
+static DEFINE_MUTEX(stl_brdslock);
 static struct stlbrd		*stl_brds[STL_MAXBRDS];
 
 /*
@@ -2303,7 +2304,6 @@
 		goto err;
 	}
 
-	stl_brds[brdp->brdnr] = brdp;
 	if ((brdp->state & BRD_FOUND) == 0) {
 		printk("STALLION: %s board not found, board=%d io=%x irq=%d\n",
 			stl_brdnames[brdp->brdtype], brdp->brdnr,
@@ -2329,8 +2329,6 @@
 	release_region(brdp->ioaddr1, brdp->iosize1);
 	if (brdp->iosize2 > 0)
 		release_region(brdp->ioaddr2, brdp->iosize2);
-
-	stl_brds[brdp->brdnr] = NULL;
 err:
 	return retval;
 }
@@ -2383,12 +2381,17 @@
 		retval = -ENOMEM;
 		goto err;
 	}
+	mutex_lock(&stl_brdslock);
 	brdp->brdnr = stl_getbrdnr();
 	if (brdp->brdnr < 0) {
 		dev_err(&pdev->dev, "too many boards found, "
 			"maximum supported %d\n", STL_MAXBRDS);
+		mutex_unlock(&stl_brdslock);
 		goto err_fr;
 	}
+	stl_brds[brdp->brdnr] = brdp;
+	mutex_unlock(&stl_brdslock);
+
 	brdp->brdtype = brdtype;
 	brdp->state |= STL_PROBED;
 
@@ -2417,11 +2420,13 @@
 	brdp->irq = pdev->irq;
 	retval = stl_brdinit(brdp);
 	if (retval)
-		goto err_fr;
+		goto err_null;
 
 	pci_set_drvdata(pdev, brdp);
 
 	return 0;
+err_null:
+	stl_brds[brdp->brdnr] = NULL;
 err_fr:
 	kfree(brdp);
 err:
@@ -4735,10 +4740,13 @@
 		brdp->irqtype = conf.irqtype;
 		if (stl_brdinit(brdp))
 			kfree(brdp);
-		else
+		else {
+			stl_brds[brdp->brdnr] = brdp;
 			stl_nrbrds = i + 1;
+		}
 	}
 
+	/* this has to be _after_ isa finding because of locking */
 	retval = pci_register_driver(&stl_pcidriver);
 	if (retval && stl_nrbrds == 0)
 		goto err;