diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 13c6eee481da..d71c7b9b9665 100644
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -275,8 +275,8 @@ static acpi_status acpi_gpiochip_alloc_event(struct acpi_resource *ares,
 	pin = agpio->pin_table[0];
 
 	if (pin <= 255) {
-		char ev_name[5];
-		sprintf(ev_name, "_%c%02hhX",
+		char ev_name[8];
+		sprintf(ev_name, "_%c%02X",
 			agpio->triggering == ACPI_EDGE_SENSITIVE ? 'E' : 'L',
 			pin);
 		if (ACPI_SUCCESS(acpi_get_handle(handle, ev_name, &evt_handle)))