diff --git a/tests/test_issues_mysqlbackend.py b/tests/test_issues_mysqlbackend.py
index 98665a092f0900326a88f201e99e0a2b5c1f1de2..c276f6a7249036247a3b7e3764fa2721f9704318 100644
--- a/tests/test_issues_mysqlbackend.py
+++ b/tests/test_issues_mysqlbackend.py
@@ -48,10 +48,9 @@ def teardown():
 
 # ########################### Issue tests start here ###########################
 
-@pytest.mark.xfail
 @with_setup(setup, teardown)
 def test_issue_18():
-    """Sometimes, duplicate parents were returned.
+    """Duplicate parents were returned in some cases of self-hineritance.
 
     Tests for https://gitlab.com/caosdb/caosdb-mysqlbackend/-/issues/18
     """
@@ -64,9 +63,9 @@ def test_issue_18():
     C.add_parent(C)  # The self-parenting is here on purpose
     C.add_parent(A)
 
-    c = db.Container()
-    c.extend([B, C, A])
-    c.insert()
+    cont = db.Container()
+    cont.extend([B, C, A])
+    cont.insert()
 
     C1 = db.Entity(name="C").retrieve()
     pids = [p.id for p in C1.parents]
diff --git a/tests/test_update.py b/tests/test_update.py
index a97d821e791e9195984d5c1ba601e46d4ca7aeeb..f783ff1339289679e1866e7ae8130560d1c76500 100644
--- a/tests/test_update.py
+++ b/tests/test_update.py
@@ -49,7 +49,8 @@ def test_property_no_id():
     rt1 = db.RecordType(name="RT1").insert()
 
     rt1.add_property(name="P1").update(raise_exception_on_error=False)
-    assert rt1.get_property("P1").get_errors()[0].description == "Entity has no ID."
+    assert rt1.get_property("P1").get_errors()[0].description \
+        == "Entity has no ID."
 
 
 def test_parent_no_id():
@@ -57,7 +58,8 @@ def test_parent_no_id():
     parent = db.RecordType(name="RTP").insert()
 
     child.add_parent(name="RTP").update(raise_exception_on_error=False)
-    assert child.get_parent("RTP").get_errors()[0].description == "Entity has no ID."
+    assert child.get_parent("RTP").get_errors()[0].description \
+        == "Entity has no ID."
 
 
 def test_update_1():
@@ -104,7 +106,8 @@ def test_server_error_during_update():
     p = db.Property(name="TestProperty", datatype="TestRT1").insert()
     p2 = db.Property(name="TestBogusProperty", datatype=db.TEXT).insert()
     rec1 = db.Record(name="TestRT1Rec1").add_parent("TestRT1").insert()
-    rec2 = db.Record(name="TestRT2Rec2").add_parent("TestRT2").add_property("TestProperty", "TestRT1Rec1").insert()
+    rec2 = db.Record(name="TestRT2Rec2").add_parent("TestRT2").add_property(
+        "TestProperty", "TestRT1Rec1").insert()
 
     # do stupid things
     rec2.get_property("TestProperty").add_property("TestBogusProperty")