diff --git a/src/bus/mod.rs b/src/bus/mod.rs
index a4ffc85..8b09625 100644
--- a/src/bus/mod.rs
+++ b/src/bus/mod.rs
@@ -4,7 +4,9 @@ mod four_wire;
 mod three_wire;
 
 pub use self::four_wire::FourWire;
+pub use self::four_wire::FourWireError;
 pub use self::three_wire::ThreeWire;
+pub use self::three_wire::ThreeWireError;
 
 pub trait Bus {
     type Error: Debug;