diff --git a/nigsp/tests/test_metrics.py b/nigsp/tests/test_metrics.py
index 8f4da29..3dd5900 100644
--- a/nigsp/tests/test_metrics.py
+++ b/nigsp/tests/test_metrics.py
@@ -3,7 +3,7 @@
 
 import numpy as np
 from numpy.random import rand
-from pytest import raises
+from pytest import raises, warns
 
 from nigsp.operations import metrics
 from nigsp.utils import prepare_ndim_iteration
@@ -73,13 +73,22 @@ def test_gsdi():
 
 
 def test_smoothness():
-    signal = rand(10, 2)
+    s1 = rand(10)
+    s2 = rand(10, 2)
+    s3 = rand(2, 10)
     laplacian = rand(10, 10)
 
-    expected_smoothness = np.dot(signal.T, np.dot(laplacian, signal))
-    computed_smoothness = metrics.smoothness(laplacian, signal)
+    expected_smoothness1 = np.dot(s1.T, np.dot(laplacian, s1))
+    expected_smoothness2 = np.dot(s2.T, np.dot(laplacian, s2))
+    expected_smoothness3 = np.dot(s3, np.dot(laplacian, s3.T))
+
+    computed_smoothness1 = metrics.smoothness(laplacian, s1)
+    computed_smoothness2 = metrics.smoothness(laplacian, s2)
+    computed_smoothness3 = metrics.smoothness(laplacian, s3)
 
-    assert (expected_smoothness == computed_smoothness).all()
+    assert (expected_smoothness1 == computed_smoothness1).all()
+    assert (expected_smoothness2 == computed_smoothness2).all()
+    assert (expected_smoothness3 == computed_smoothness3).all()
 
 
 # ### Break tests