diff --git a/test/algorithm_test/FilterAlgorithm_test.py b/test/algorithm_test/FilterAlgorithm_test.py
index b03a372371bfcb33694fdc783dd59b53ed5eea62..bc98a21e6dfafff63b5e31a32a7664e3365ee16d 100644
--- a/test/algorithm_test/FilterAlgorithm_test.py
+++ b/test/algorithm_test/FilterAlgorithm_test.py
@@ -49,6 +49,7 @@ def test_second():
     assert_almost_equal(u_filt.data, u.data, 2)
     assert_almost_equal(v_filt.data, v.data, 2)
     assert_almost_equal(w_filt.data, w.data, 2)
+    assert_equal(filtered[0].times(), LLO[0].times())
 
 
 def test_minute():
@@ -90,6 +91,7 @@ def test_minute():
     assert_almost_equal(u_filt.data, u.data, 2)
     assert_almost_equal(v_filt.data, v.data, 2)
     assert_almost_equal(w_filt.data, w.data, 2)
+    assert_equal(filtered[0].times(), LLO[0].times())
 
 
 def test_hour():
@@ -132,6 +134,7 @@ def test_hour():
     assert_almost_equal(e_filt.data, e.data, 2)
     assert_almost_equal(z_filt.data, z.data, 2)
     assert_almost_equal(f_filt.data, f.data, 2)
+    assert_equal(filtered[0].times(), BOU[0].times())
 
 
 def test_day():
@@ -174,6 +177,7 @@ def test_day():
     assert_almost_equal(e_filt.data, e.data, 2)
     assert_almost_equal(z_filt.data, z.data, 2)
     assert_almost_equal(f_filt.data, f.data, 2)
+    assert_equal(filtered[0].times(), BOU[0].times())
 
 
 def test_custom():
@@ -219,6 +223,7 @@ def test_custom():
     assert_almost_equal(u_filt.data, u.data, 2)
     assert_almost_equal(v_filt.data, v.data, 2)
     assert_almost_equal(w_filt.data, w.data, 2)
+    assert_equal(filtered[0].times(), LLO[0].times())
 
 
 def test_starttime_shift():