diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index d0608ae5..67343d6e 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        python-version: ["3.5", "3.6", "3.7", "3.8", "3.9"]
+        python-version: ["3.5", "3.6", "3.7", "3.8", "3.9", "3.10"]
 
     steps:
       - name: Checkout source
diff --git a/pyerrors/correlators.py b/pyerrors/correlators.py
index ff899dc8..ee949276 100644
--- a/pyerrors/correlators.py
+++ b/pyerrors/correlators.py
@@ -427,7 +427,7 @@ class Corr:
             if isinstance(save, str):
                 fig.savefig(save)
             else:
-                raise Exception('safe has to be a string.')
+                raise Exception("Safe has to be a string.")
 
         return
 
diff --git a/tests/test_correlators.py b/tests/test_correlators.py
index 37b59fba..502f26fa 100644
--- a/tests/test_correlators.py
+++ b/tests/test_correlators.py
@@ -1,3 +1,4 @@
+import os
 import numpy as np
 import pyerrors as pe
 import pytest
@@ -46,3 +47,27 @@ def test_modify_correlator():
     corr.deriv(symmetric=True)
     corr.deriv(symmetric=False)
     corr.second_deriv()
+
+def test_m_eff():
+    my_corr = pe.correlators.Corr([pe.pseudo_Obs(10, 0.1, 't'), pe.pseudo_Obs(9, 0.05, 't')])
+    my_corr.m_eff('log')
+    my_corr.m_eff('cosh')
+
+def test_utility():
+    corr_content = []
+    for t in range(8):
+        exponent = np.random.normal(3, 5)
+        corr_content.append(pe.pseudo_Obs(2 + 10 ** exponent, 10 ** (exponent - 1), 't'))
+
+    corr = pe.correlators.Corr(corr_content)
+    corr.print()
+    corr.print([2, 4])
+    corr.show()
+
+    corr.dump('test_dump')
+    new_corr = pe.load_object('test_dump.p')
+    os.remove('test_dump.p')
+    for o_a, o_b in zip(corr.content, new_corr.content):
+        assert np.isclose(o_a[0].value, o_b[0].value)
+        assert np.isclose(o_a[0].dvalue, o_b[0].dvalue)
+        assert np.allclose(o_a[0].deltas['t'], o_b[0].deltas['t'])