diff --git a/pygmx/utility.pxd b/pygmx/utility.pxd
index d9c1061..05a45d6 100644
--- a/pygmx/utility.pxd
+++ b/pygmx/utility.pxd
@@ -2,13 +2,10 @@
 
 from libc.stdint cimport int64_t
 
-#cdef extern from "inttypes.h":
-ctypedef unsigned long __int64
-ctypedef int64_t gmx_int64_t
 
 cdef extern from "gromacs/utility/basedefinitions.h":
     ctypedef int gmx_bool
-    ctypedef __int64 gmx_int64_t
+    ctypedef int64_t gmx_int64_t
 
 cdef extern from "gromacs/utility/real.h":
     ctypedef double real