diff --git a/drivers/usb/mtu3/mtu3_core.c b/drivers/usb/mtu3/mtu3_core.c
index 520e55a760c9..603b7f84d31e 100644
--- a/drivers/usb/mtu3/mtu3_core.c
+++ b/drivers/usb/mtu3/mtu3_core.c
@@ -696,7 +696,7 @@ static irqreturn_t mtu3_u2_common_isr(struct mtu3 *mtu)
 	return IRQ_HANDLED;
 }
 
-irqreturn_t mtu3_irq(int irq, void *data)
+static irqreturn_t mtu3_irq(int irq, void *data)
 {
 	struct mtu3 *mtu = (struct mtu3 *)data;
 	unsigned long flags;
diff --git a/drivers/usb/mtu3/mtu3_qmu.c b/drivers/usb/mtu3/mtu3_qmu.c
index a6dd292c63ec..7d9ba8a52368 100644
--- a/drivers/usb/mtu3/mtu3_qmu.c
+++ b/drivers/usb/mtu3/mtu3_qmu.c
@@ -168,7 +168,7 @@ static struct qmu_gpd *advance_deq_gpd(struct mtu3_gpd_ring *ring)
 }
 
 /* check if a ring is emtpy */
-int gpd_ring_empty(struct mtu3_gpd_ring *ring)
+static int gpd_ring_empty(struct mtu3_gpd_ring *ring)
 {
 	struct qmu_gpd *enq = ring->enqueue;
 	struct qmu_gpd *next;