diff --git a/sys/dev/mpt/mpt_pci.c b/sys/dev/mpt/mpt_pci.c
index 57289586de6f..7a3ff0a7e8c2 100644
--- a/sys/dev/mpt/mpt_pci.c
+++ b/sys/dev/mpt/mpt_pci.c
@@ -300,7 +300,7 @@ mpt_set_options(struct mpt_softc *mpt)
 	tval = 0;
 	if (resource_int_value(device_get_name(mpt->dev),
 	    device_get_unit(mpt->dev), "debug", &tval) == 0 && tval != 0) {
-		mpt->verbose += tval;
+		mpt->verbose = tval;
 	}
 	tval = 0;
 	if (resource_int_value(device_get_name(mpt->dev),