diff --git a/pyproject.toml b/pyproject.toml
index 5ede549..954c82f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -2,7 +2,7 @@
 requires = [
     "wheel",
     "setuptools",
-    "cython>=0.28.0,<=0.29.36", # Cython 3.0.0 causes #95
+    "cython>=0.28.0",
     "numpy>=v1.20.0",
     "scipy",
 ]
diff --git a/pysptk/_sptk.pyx b/pysptk/_sptk.pyx
index 47ec476..a7bd0bf 100644
--- a/pysptk/_sptk.pyx
+++ b/pysptk/_sptk.pyx
@@ -5,7 +5,7 @@ import numpy as np
 cimport numpy as np
 
 cimport cython
-cimport _sptk
+from . cimport _sptk
 
 from warnings import warn
 from pysptk.util import assert_gamma, assert_fftlen, assert_pade, assert_stage