diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index a0b5becf91fa..8dc0466a9307 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -561,7 +561,7 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata,
 
 	if (chip) {
 		struct attribute **attrs;
-		int ngroups = 2;
+		int ngroups = 2; /* terminating NULL plus &hwdev->groups */
 
 		if (groups)
 			for (i = 0; groups[i]; i++)