diff --git a/libnfc/buses/usbbus.c b/libnfc/buses/usbbus.c
index d3ff362..6385d33 100644
--- a/libnfc/buses/usbbus.c
+++ b/libnfc/buses/usbbus.c
@@ -199,7 +199,7 @@ static int find_busses(struct usbbus_bus **ret)
 
     memset(bus, 0, sizeof(*bus));
     bus->location = bus_num;
-    sprintf(bus->dirname, "%03d", bus_num);
+    snprintf(bus->dirname, USBBUS_PATH_MAX, "%03d", bus_num);
     LIST_ADD(busses, bus);
   }
 
@@ -303,7 +303,7 @@ static int find_devices(libusb_device **dev_list, int dev_list_len,
 
     dev->bus = bus;
     dev->devnum = libusb_get_device_address(newlib_dev);
-    sprintf(dev->filename, "%03d", dev->devnum);
+    snprintf(dev->filename, USBBUS_PATH_MAX, "%03d", dev->devnum);
     LIST_ADD(devices, dev);
   }