diff --git a/drivers/mfd/wm831x-core.c b/drivers/mfd/wm831x-core.c
index a3d5728b6449..f2ab025ad97a 100644
--- a/drivers/mfd/wm831x-core.c
+++ b/drivers/mfd/wm831x-core.c
@@ -349,6 +349,9 @@ int wm831x_auxadc_read(struct wm831x *wm831x, enum wm831x_auxadc input)
 		goto disable;
 	}
 
+	/* If an interrupt arrived late clean up after it */
+	try_wait_for_completion(&wm831x->auxadc_done);
+
 	/* Ignore the result to allow us to soldier on without IRQ hookup */
 	wait_for_completion_timeout(&wm831x->auxadc_done, msecs_to_jiffies(5));
 
diff --git a/drivers/mfd/wm8350-core.c b/drivers/mfd/wm8350-core.c
index e400a3bed063..b5807484b4c9 100644
--- a/drivers/mfd/wm8350-core.c
+++ b/drivers/mfd/wm8350-core.c
@@ -363,6 +363,10 @@ int wm8350_read_auxadc(struct wm8350 *wm8350, int channel, int scale, int vref)
 	reg |= 1 << channel | WM8350_AUXADC_POLL;
 	wm8350_reg_write(wm8350, WM8350_DIGITISER_CONTROL_1, reg);
 
+	/* If a late IRQ left the completion signalled then consume
+	 * the completion. */
+	try_wait_for_completion(&wm8350->auxadc_done);
+
 	/* We ignore the result of the completion and just check for a
 	 * conversion result, allowing us to soldier on if the IRQ
 	 * infrastructure is not set up for the chip. */