diff --git a/src/dbus_fast/_private/constants.py b/src/dbus_fast/_private/constants.py
index 5ab7aef..605c3cf 100644
--- a/src/dbus_fast/_private/constants.py
+++ b/src/dbus_fast/_private/constants.py
@@ -16,6 +16,3 @@ class HeaderField(Enum):
     SENDER = 7
     SIGNATURE = 8
     UNIX_FDS = 9
-
-
-HEADER_NAME_MAP = {field.value: field.name for field in HeaderField}
diff --git a/src/dbus_fast/_private/unmarshaller.pxd b/src/dbus_fast/_private/unmarshaller.pxd
index 76fba2d..2447ddc 100644
--- a/src/dbus_fast/_private/unmarshaller.pxd
+++ b/src/dbus_fast/_private/unmarshaller.pxd
@@ -5,16 +5,6 @@ import cython
 from ..signature import SignatureType
 
 
-cdef str HEADER_DESTINATION
-cdef str HEADER_PATH
-cdef str HEADER_INTERFACE
-cdef str HEADER_MEMBER
-cdef str HEADER_ERROR_NAME
-cdef str HEADER_REPLY_SERIAL
-cdef str HEADER_SENDER
-cdef str HEADER_SIGNATURE
-
-
 cdef unsigned int UINT32_SIZE
 cdef unsigned int INT16_SIZE
 cdef unsigned int HEADER_ARRAY_OF_STRUCT_SIGNATURE_POSITION
diff --git a/src/dbus_fast/_private/unmarshaller.py b/src/dbus_fast/_private/unmarshaller.py
index 078e49a..5809a3b 100644
--- a/src/dbus_fast/_private/unmarshaller.py
+++ b/src/dbus_fast/_private/unmarshaller.py
@@ -9,7 +9,7 @@ from ..constants import MESSAGE_FLAG_MAP, MESSAGE_TYPE_MAP
 from ..errors import InvalidMessageError
 from ..message import Message
 from ..signature import SignatureType, Variant, get_signature_tree
-from .constants import BIG_ENDIAN, LITTLE_ENDIAN, PROTOCOL_VERSION, HeaderField
+from .constants import BIG_ENDIAN, LITTLE_ENDIAN, PROTOCOL_VERSION
 
 IS_LITTLE_ENDIAN = sys.byteorder == "little"
 IS_BIG_ENDIAN = sys.byteorder == "big"