diff --git a/drivers/mfd/adp5520.c b/drivers/mfd/adp5520.c
index 401a9b6029e3540e0d4ea903a161f409e7f6afd3..b26644772d02fee2fc32ef6dd97ed69d0c052f5b 100644
--- a/drivers/mfd/adp5520.c
+++ b/drivers/mfd/adp5520.c
@@ -66,7 +66,8 @@ static int __adp5520_write(struct i2c_client *client,
 	return 0;
 }
 
-int __adp5520_ack_bits(struct i2c_client *client, int reg, uint8_t bit_mask)
+static int __adp5520_ack_bits(struct i2c_client *client, int reg,
+			      uint8_t bit_mask)
 {
 	struct adp5520_chip *chip = i2c_get_clientdata(client);
 	uint8_t reg_val;