diff --git a/drivers/mfd/wm831x-irq.c b/drivers/mfd/wm831x-irq.c
index 1808deb..6c3408c 100644
--- a/drivers/mfd/wm831x-irq.c
+++ b/drivers/mfd/wm831x-irq.c
@@ -408,6 +408,11 @@
 			return -EINVAL;
 	}
 
+	/* Rebase the IRQ into the GPIO range so we've got a sensible array
+	 * index.
+	 */
+	irq -= WM831X_IRQ_GPIO_1;
+
 	/* We set the high bit to flag that we need an update; don't
 	 * do the update here as we can be called with the bus lock
 	 * held.