diff --git a/io/i2c/devfs.go b/io/i2c/devfs.go
index 481713b..177ccca 100644
--- a/io/i2c/devfs.go
+++ b/io/i2c/devfs.go
@@ -37,7 +37,7 @@
 // TODO(jbd): Support I2C_RETRIES and I2C_TIMEOUT at the driver and implementation level.
 
 func (d *Devfs) Open(bus, addr int) (driver.Conn, error) {
-	f, err := os.OpenFile(fmt.Sprintf("/dev/i2c-%d", bus), os.O_RDWR, 0)
+	f, err := os.OpenFile(fmt.Sprintf("/dev/i2c-%d", bus), os.O_RDWR, os.ModeDevice)
 	if err != nil {
 		return nil, err
 	}
diff --git a/io/spi/devfs.go b/io/spi/devfs.go
index 0df5ee6..f4a2177 100644
--- a/io/spi/devfs.go
+++ b/io/spi/devfs.go
@@ -50,7 +50,7 @@
 // Open Devfs /dev/spidev<bus>.<chip> and returns a connection.
 func (d *Devfs) Open(bus, chip int) (driver.Conn, error) {
 	n := fmt.Sprintf("/dev/spidev%d.%d", bus, chip)
-	f, err := os.OpenFile(n, os.O_RDWR, 0)
+	f, err := os.OpenFile(n, os.O_RDWR, os.ModeDevice)
 	if err != nil {
 		return nil, err
 	}