diff --git a/srsly/msgpack/_unpacker.pyx b/srsly/msgpack/_unpacker.pyx
index b6c5f04..17a0059 100644
--- a/srsly/msgpack/_unpacker.pyx
+++ b/srsly/msgpack/_unpacker.pyx
@@ -10,7 +10,6 @@ cdef extern from "Python.h":
 from libc.stdlib cimport *
 from libc.string cimport *
 from libc.limits cimport *
-ctypedef unsigned long long uint64_t
 
 from .exceptions import (
     BufferFull,
