diff --git a/demo/horizontal/emmo2meta.py b/demo/horizontal/emmo2meta.py
index 9ca36036d..1c4538938 100644
--- a/demo/horizontal/emmo2meta.py
+++ b/demo/horizontal/emmo2meta.py
@@ -174,7 +174,7 @@ def get_properties(self, cls):  # pylint: disable=too-many-locals
         props = []
         dimindices = {}
         propnames = set()
-        types = dict(Integer="int", Real="double", String="string")
+        types = {"Integer": "int", "Real": "double", "String": "string"}
 
         def get_dim(restriction, name, descr=None):
             """Returns dimension index corresponding to dimension name `name`
diff --git a/ontopy/graph.py b/ontopy/graph.py
index ec142243a..ba69d4dff 100644
--- a/ontopy/graph.py
+++ b/ontopy/graph.py
@@ -264,7 +264,7 @@ def __init__(  # pylint: disable=too-many-arguments,too-many-locals
             self.edges = set()
         else:
             if ontology != graph.ontology:
-                ValueError(
+                raise ValueError(
                     "the same ontology must be used when extending a graph"
                 )
             self.dot = graph.dot.copy()
diff --git a/ontopy/ontodoc.py b/ontopy/ontodoc.py
index 3092d13bc..e14637e1c 100644
--- a/ontopy/ontodoc.py
+++ b/ontopy/ontodoc.py
@@ -49,20 +49,20 @@ class OntoDoc:
             annotation values.
     """
 
-    _markdown_style = dict(
-        sep="\n",
-        figwidth="{{ width={width:.0f}px }}",
-        figure="![{caption}]({path}){figwidth}\n",
-        header="\n{:#<{level}} {label}",
-        link="[{name}]({lowerurl})",
-        point="  - {point}\n",
-        points="\n\n{points}\n",
-        annotation="**{key}:** {value}\n",
-        substitutions=[],
-    )
+    _markdown_style = {
+        "sep": "\n",
+        "figwidth": "{{ width={width:.0f}px }}",
+        "figure": "![{caption}]({path}){figwidth}\n",
+        "header": "\n{:#<{level}} {label}",
+        "link": "[{name}]({lowerurl})",
+        "point": "  - {point}\n",
+        "points": "\n\n{points}\n",
+        "annotation": "**{key}:** {value}\n",
+        "substitutions": [],
+    }
     # Extra style settings for markdown+tex (e.g. pdf generation with pandoc)
-    _markdown_tex_extra_style = dict(
-        substitutions=[
+    _markdown_tex_extra_style = {
+        "substitutions": [
             # logic/math symbols
             ("\u2200", r"$\\forall$"),
             ("\u2203", r"$\\exists$"),
@@ -132,17 +132,17 @@ class OntoDoc:
             ("\u014d", r"$\\bar{\\mathrm{o}}$"),
             ("\u1f45", r"$\\acute{o}$"),  # no \omicron
         ],
-    )
-    _html_style = dict(
-        sep="<p>\n",
-        figwidth='width="{width:.0f}"',
-        figure='<img src="{path}" alt="{caption}"{figwidth}>',
-        header='<h{level} id="{lowerlabel}">{label}</h{level}>',
-        link='<a href="{lowerurl}">{name}</a>',
-        point="      <li>{point}</li>\n",
-        points="    <ul>\n      {points}\n    </ul>\n",
-        annotation="  <dd><strong>{key}:</strong>\n{value}  </dd>\n",
-        substitutions=[
+    }
+    _html_style = {
+        "sep": "<p>\n",
+        "figwidth": 'width="{width:.0f}"',
+        "figure": '<img src="{path}" alt="{caption}"{figwidth}>',
+        "header": '<h{level} id="{lowerlabel}">{label}</h{level}>',
+        "link": '<a href="{lowerurl}">{name}</a>',
+        "point": "      <li>{point}</li>\n",
+        "points": "    <ul>\n      {points}\n    </ul>\n",
+        "annotation": "  <dd><strong>{key}:</strong>\n{value}  </dd>\n",
+        "substitutions": [
             (r"&", r"&#8210;"),
             (r"<p>", r"<p>\n\n"),
             (r"\u2018([^\u2019]*)\u2019", r"<q>\1</q>"),
@@ -154,7 +154,7 @@ class OntoDoc:
             (r"\u226B", r"&x226B;"),
             (r'"Y$', r""),  # strange noice added by owlready2
         ],
-    )
+    }
 
     def __init__(self, onto, style="markdown"):
         if isinstance(style, str):
@@ -243,15 +243,15 @@ def itemdoc(
         substitutions = self.style.get("substitutions", [])
 
         # Logical "sorting" of annotations
-        order = dict(
-            definition="00",
-            axiom="01",
-            theorem="02",
-            elucidation="03",
-            domain="04",
-            range="05",
-            example="06",
-        )
+        order = {
+            "definition": "00",
+            "axiom": "01",
+            "theorem": "02",
+            "elucidation": "03",
+            "domain": "04",
+            "range": "05",
+            "example": "06",
+        }
 
         doc = []
 
@@ -409,7 +409,6 @@ def itemdoc(
                         key="Individuals", value=value, ontology=onto
                     )
                 )
-
         return "\n".join(doc)
 
     def itemsdoc(self, items, header_level=3):
diff --git a/ontopy/ontology.py b/ontopy/ontology.py
index 90eed6c08..d3fd267b1 100644
--- a/ontopy/ontology.py
+++ b/ontopy/ontology.py
@@ -220,8 +220,7 @@ def __contains__(self, other):
             self.get_by_label(other)
         except NoSuchLabelError:
             return False
-        else:
-            return True
+        return True
 
     def __objclass__(self):
         # Play nice with inspect...
@@ -782,7 +781,7 @@ def save(
                 fmt = revmap.get(format, format)
                 filename = f"{self.name}.{fmt}"
             else:
-                TypeError("`filename` and `format` cannot both be None.")
+                raise TypeError("`filename` and `format` cannot both be None.")
         filename = os.path.join(dir, filename)
         dir = Path(filename).resolve().parent
 
@@ -1465,7 +1464,9 @@ def closest_common_ancestor(*classes):
                     return cur
                 if len(mro) == 0:
                     mros.remove(mro)
-        raise Exception("A closest common ancestor should always exist !")
+        raise EMMOntoPyException(
+            "A closest common ancestor should always exist !"
+        )
 
     def get_ancestors(self, classes, include="all", strict=True):
         """Return ancestors of all classes in `classes`.
diff --git a/ontopy/patch.py b/ontopy/patch.py
index d67525dcb..6a957e2cc 100644
--- a/ontopy/patch.py
+++ b/ontopy/patch.py
@@ -5,6 +5,7 @@
 import owlready2
 from owlready2 import ThingClass, PropertyClass, Thing, Restriction, Namespace
 from owlready2 import Metadata
+from ontopy.utils import EMMOntoPyException
 
 
 def render_func(entity):
@@ -60,7 +61,9 @@ def get_parents(self, strict=False):
             for cls in self.is_a
             if isinstance(cls, owlready2.ObjectPropertyClass)
         }
-    raise Exception("self has no parents - this should not be possible!")
+    raise EMMOntoPyException(
+        "self has no parents - this should not be possible!"
+    )
 
 
 def _dir(self):