diff --git a/experimental/devices/bitbang/spi.go b/experimental/devices/bitbang/spi.go
index 99268b0..51f8bd3 100644
--- a/experimental/devices/bitbang/spi.go
+++ b/experimental/devices/bitbang/spi.go
@@ -57,7 +57,7 @@ func (s *SPI) Configure(mode spi.Mode, bits int) error {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 	if mode != spi.Mode3 {
-		return errors.New("not implemented")
+		return errors.New("bitbang-spi: not implemented")
 	}
 	s.mode = mode
 	s.bits = bits