diff --git a/src/newcrawler/converters.py b/src/newcrawler/converters.py
index f7a491667c96b3ba99bae3f64df573b373b5b34a..caf1aa667a8cbb26021c2b3feeb347a168fa95b4 100644
--- a/src/newcrawler/converters.py
+++ b/src/newcrawler/converters.py
@@ -197,8 +197,7 @@ class Converter(object):
                           converter_registry: dict):
 
         if "type" not in definition:
-            raise RuntimeError(
-                "Type is mandatory for converter entries in CFood definition.")
+            raise RuntimeError("Type is mandatory for converter entries in CFood definition.")
 
         if definition["type"] not in converter_registry:
             raise RuntimeError("Unknown Type: {}".format(definition["type"]))
@@ -265,8 +264,7 @@ class DirectoryConverter(Converter):
     def create_children(self, generalStore: GeneralStore,
                         element: StructureElement):
         if not isinstance(element, Directory):
-            raise RuntimeError(
-                "Directory converters can only create children from directories.")
+            raise RuntimeError("Directory converters can only create children from directories.")
 
         return self.create_children_from_directory(element)
 
@@ -336,8 +334,7 @@ class MarkdownFileConverter(Converter):
         if not isinstance(element, File):
             raise RuntimeError("A markdown file is needed to create children.")
 
-        header = yaml_header_tools.get_header_from_file(
-            element.path, clean=False)
+        header = yaml_header_tools.get_header_from_file(element.path, clean=False)
         children: list[StructureElement] = []
 
         for name, entry in header.items():
@@ -346,8 +343,7 @@ class MarkdownFileConverter(Converter):
             elif type(entry) == str:
                 children.append(DictTextElement(name, entry))
             else:
-                raise RuntimeError(
-                    "Header entry {} has incompatible type.".format(name))
+                raise RuntimeError("Header entry {} has incompatible type.".format(name))
         return children
 
     def typecheck(self, element: StructureElement):
@@ -476,8 +472,7 @@ class DictListElementConverter(Converter):
     def create_children(self, generalStore: GeneralStore,
                         element: StructureElement):
         if not isinstance(element, DictListElement):
-            raise RuntimeError(
-                "This converter can only process DictListElements.")
+            raise RuntimeError("This converter can only process DictListElements.")
         return [TextElement(str(index), list_element) for index, list_element in enumerate(element.value)]
 
     def typecheck(self, element: StructureElement):
@@ -490,8 +485,7 @@ class DictListElementConverter(Converter):
         if m is None:
             return None
         if "match" in self.definition:
-            raise NotImplementedError(
-                "Match is not implemented for DictListElement.")
+            raise NotImplementedError("Match is not implemented for DictListElement.")
         return m.groupdict()
 
 
diff --git a/tox.ini b/tox.ini
index 161c1d743e3861039625fc7b181c0c9fff25e311..8b5ad34fb1583790de5365f2bfa4ff7b3704574c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,3 +7,5 @@ deps = .
     pytest
     pytest-cov
 commands=py.test --cov=caosdb -vv {posargs}
+[flake8]
+max-line-length=100