diff --git a/components/ocs_io/i2c/types.h b/components/ocs_io/i2c/types.h
index 9d960141..c04fc371 100644
--- a/components/ocs_io/i2c/types.h
+++ b/components/ocs_io/i2c/types.h
@@ -11,6 +11,9 @@ namespace ocs {
 namespace io {
 namespace i2c {
 
+//! I2C address.
+using Address = uint16_t;
+
 enum class TransferSpeed : uint8_t {
     //! 100 kbit/s.
     Default,
@@ -27,9 +30,6 @@ enum class AddressLength : uint8_t {
     Bit_10,
 };
 
-//! I2C address.
-using Address = uint16_t;
-
 } // namespace i2c
 } // namespace io
 } // namespace ocs