diff --git a/tests/test_RuLSIF.py b/tests/test_RuLSIF.py
index de83d2e..dbe7029 100644
--- a/tests/test_RuLSIF.py
+++ b/tests/test_RuLSIF.py
@@ -1,7 +1,7 @@
 import unittest
 
 from scipy.stats import norm, multivariate_normal
-from numpy import linspace
+from numpy import linspace, mgrid
 from .context import densratio
 
 
@@ -45,7 +45,9 @@ def test_alphadensratio_2d(self):
         y = multivariate_normal.rvs(size=300, mean=[1, 1], cov=[[1./2, 0], [0, 2]], random_state=71)
         result = densratio(x, y, alpha=0.5)
         self.assertIsNotNone(result)
-        density_ratio = result.compute_density_ratio(linspace(-1, 3))
+        space_range = slice(-1, 3, 50j)
+        space_2d = mgrid[space_range, space_range].reshape(2, -1).T
+        density_ratio = result.compute_density_ratio(space_2d)
         self.assertTrue((density_ratio >= 0).all())
 
     def test_densratio_dimension_error(self):