diff --git a/geotiepoints/multilinear.py b/geotiepoints/multilinear.py
index e6cf5f7..b3bf2b7 100644
--- a/geotiepoints/multilinear.py
+++ b/geotiepoints/multilinear.py
@@ -61,7 +61,7 @@ class MultilinearInterpolator:
     def __init__(self, smin, smax, orders, values=None, dtype=np.float64):
         self.smin = np.asarray(smin, dtype=dtype)
         self.smax = np.asarray(smax, dtype=dtype)
-        self.orders = np.asarray(orders, dtype=np.int_)
+        self.orders = np.asarray(orders, dtype=np.int64)
         self.d = len(orders)
         self.dtype = dtype
         if values is not None:
diff --git a/geotiepoints/multilinear_cython.pyx b/geotiepoints/multilinear_cython.pyx
index 6133d2a..3392fa1 100644
--- a/geotiepoints/multilinear_cython.pyx
+++ b/geotiepoints/multilinear_cython.pyx
@@ -10,7 +10,7 @@ import numpy as np
 np.import_array()
 
 
-def multilinear_interpolation(floating[:] smin, floating[:] smax, int[:] orders, floating[:,::1] values, floating[:,::1] s):
+def multilinear_interpolation(floating[:] smin, floating[:] smax, np.int64_t[:] orders, floating[:,::1] values, floating[:,::1] s):
 
     cdef Py_ssize_t d = s.shape[0]
     cdef Py_ssize_t n_s = s.shape[1]
@@ -46,7 +46,7 @@ def multilinear_interpolation(floating[:] smin, floating[:] smax, int[:] orders,
 
 
 cdef void multilinear_interpolation_1d(floating[:] smin, floating[:] smax,
-                                       int[:] orders, floating[:] V,
+                                       np.int64_t[:] orders, floating[:] V,
                                        int n_s, floating[:,::1] s, floating[:] output) noexcept nogil:
 
     cdef int i
@@ -79,7 +79,7 @@ cdef void multilinear_interpolation_1d(floating[:] smin, floating[:] smax,
 
 
 cdef void multilinear_interpolation_2d(floating[:] smin, floating[:] smax,
-                                       int[:] orders, floating[:] V,
+                                       np.int64_t[:] orders, floating[:] V,
                                        int n_s, floating[:,::1] s, floating[:] output) noexcept nogil:
 
     cdef int i
@@ -124,7 +124,7 @@ cdef void multilinear_interpolation_2d(floating[:] smin, floating[:] smax,
 
 
 cdef void multilinear_interpolation_3d(floating[:] smin, floating[:] smax,
-                                       int[:] orders, floating[:] V,
+                                       np.int64_t[:] orders, floating[:] V,
                                        int n_s, floating[:,::1] s, floating[:] output) noexcept nogil:
     cdef int i
     cdef floating lam_0, s_0, sn_0, snt_0
@@ -184,7 +184,7 @@ cdef void multilinear_interpolation_3d(floating[:] smin, floating[:] smax,
 
 
 cdef void multilinear_interpolation_4d(floating[:] smin, floating[:] smax,
-                                       int[:] orders, floating[:] V,
+                                       np.int64_t[:] orders, floating[:] V,
                                        int n_s, floating[:,::1] s, floating[:] output) noexcept nogil:
 
     cdef int i
@@ -269,7 +269,7 @@ cdef void multilinear_interpolation_4d(floating[:] smin, floating[:] smax,
 
 
 cdef void multilinear_interpolation_5d(floating[:] smin, floating[:] smax,
-                                       int[:] orders, floating[:] V,
+                                       np.int64_t[:] orders, floating[:] V,
                                        int n_s, floating[:,::1] s, floating[:] output) noexcept nogil:
     cdef int i
     cdef floating lam_0, s_0, sn_0, snt_0