diff --git a/tests/keras_contrib/backend/backend_test.py b/tests/keras_contrib/backend/backend_test.py
index 998bc6b..1e4f344 100644
--- a/tests/keras_contrib/backend/backend_test.py
+++ b/tests/keras_contrib/backend/backend_test.py
@@ -157,8 +157,9 @@ class TestBackend(object):
                     th_var_val = KTH.eval(th_var)
                     tf_var_val = KTF.eval(tf_var)
 
-                    assert_allclose(th_mean_val, tf_mean_val, rtol=1e-4)
-                    assert_allclose(th_var_val, tf_var_val, rtol=1e-4)
+                    # absolute tolerance needed when working with zeros
+                    assert_allclose(th_mean_val, tf_mean_val, rtol=1e-4, atol=1e-10)
+                    assert_allclose(th_var_val, tf_var_val, rtol=1e-4, atol=1e-10)
 
     def test_clip(self):
         check_single_tensor_operation('clip', (4, 2), min_value=0.4, max_value=0.6)