diff --git a/pyproject.toml b/pyproject.toml
index 26a3957bd..2edb51eb1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -139,7 +139,6 @@ ignore_missing_imports = true
 [[tool.mypy.overrides]]
 module = [
   'sphinx_needs.api.need',
-  'sphinx_needs.directives.needuml',
 ]
 ignore_errors = true
 
diff --git a/sphinx_needs/diagrams_common.py b/sphinx_needs/diagrams_common.py
index 0eced3edb..760e680e9 100644
--- a/sphinx_needs/diagrams_common.py
+++ b/sphinx_needs/diagrams_common.py
@@ -17,7 +17,7 @@
 from sphinx.util.docutils import SphinxDirective
 
 from sphinx_needs.config import NeedsSphinxConfig
-from sphinx_needs.data import NeedsFilteredBaseType, NeedsPartsInfoType
+from sphinx_needs.data import NeedsFilteredBaseType, NeedsInfoType, NeedsPartsInfoType
 from sphinx_needs.errors import NoUri
 from sphinx_needs.logging import get_logger
 from sphinx_needs.utils import get_scale, split_link_types
@@ -169,7 +169,7 @@ def get_debug_container(puml_node: nodes.Element) -> nodes.container:
 
 
 def calculate_link(
-    app: Sphinx, need_info: NeedsPartsInfoType, _fromdocname: str
+    app: Sphinx, need_info: NeedsInfoType | NeedsPartsInfoType, _fromdocname: None | str
 ) -> str:
     """
     Link calculation
diff --git a/sphinx_needs/directives/needuml.py b/sphinx_needs/directives/needuml.py
index 3fd8f3b41..326bd4430 100644
--- a/sphinx_needs/directives/needuml.py
+++ b/sphinx_needs/directives/needuml.py
@@ -2,7 +2,7 @@
 
 import html
 import os
-from typing import Sequence
+from typing import TYPE_CHECKING, Any, Dict, List, Sequence, TypedDict
 
 from docutils import nodes
 from docutils.parsers.rst import directives
@@ -11,13 +11,25 @@
 from sphinx.util.docutils import SphinxDirective
 
 from sphinx_needs.config import NeedsSphinxConfig
-from sphinx_needs.data import SphinxNeedsData
+from sphinx_needs.data import NeedsInfoType, SphinxNeedsData
 from sphinx_needs.debug import measure_time
 from sphinx_needs.diagrams_common import calculate_link
 from sphinx_needs.directives.needflow import make_entity_name
 from sphinx_needs.filter_common import filter_needs
 from sphinx_needs.utils import add_doc
 
+if TYPE_CHECKING:
+    from sphinxcontrib.plantuml import plantuml
+
+
+class ProcessedDataType(TypedDict):
+    art: str
+    key: None | str
+    arguments: dict[str, Any]
+
+
+ProcessedNeedsType = Dict[str, List[ProcessedDataType]]
+
 
 class Needuml(nodes.General, nodes.Element):
     pass
@@ -130,8 +142,13 @@ def run(self) -> Sequence[nodes.Node]:
 
 
 def transform_uml_to_plantuml_node(
-    app, uml_content: str, parent_need_id: str, key: str, kwargs: dict, config: str
-):
+    app: Sphinx,
+    uml_content: str,
+    parent_need_id: None | str,
+    key: None | str,
+    kwargs: dict[str, Any],
+    config: str,
+) -> plantuml:
     try:
         if "sphinxcontrib.plantuml" not in app.config.extensions:
             raise ImportError
@@ -158,7 +175,7 @@ def transform_uml_to_plantuml_node(
         puml_node["uml"] += "\n\n"
 
     # jinja2uml to translate jinja statements to uml text
-    (uml_content_return, processed_need_ids_return) = jinja2uml(
+    (uml_content_return, _) = jinja2uml(
         app=app,
         fromdocname=None,
         uml_content=uml_content,
@@ -167,16 +184,15 @@ def transform_uml_to_plantuml_node(
         processed_need_ids={},
         kwargs=kwargs,
     )
-    # silently discard processed_need_ids_return
 
     puml_node["uml"] += f"\n{uml_content_return}"
     puml_node["uml"] += "\n@enduml\n"
     return puml_node
 
 
-def get_debug_node_from_puml_node(puml_node):
+def get_debug_node_from_puml_node(puml_node: plantuml) -> nodes.container:
     if isinstance(puml_node, nodes.figure):
-        data = puml_node.children[0]["uml"]
+        data = puml_node.children[0]["uml"]  # type: ignore[index]
     data = puml_node.get("uml", "")
     data = "\n".join([html.escape(line) for line in data.split("\n")])
     debug_para = nodes.raw("", f"<pre>{data}</pre>", format="html")
@@ -186,20 +202,20 @@ def get_debug_node_from_puml_node(puml_node):
 
 
 def jinja2uml(
-    app,
-    fromdocname,
+    app: Sphinx,
+    fromdocname: None | str,
     uml_content: str,
-    parent_need_id: str,
-    key: str,
-    processed_need_ids: {},
-    kwargs: dict,
-) -> (str, {}):
+    parent_need_id: None | str,
+    key: None | str,
+    processed_need_ids: ProcessedNeedsType,
+    kwargs: dict[str, Any],
+) -> tuple[str, ProcessedNeedsType]:
     # Let's render jinja templates with uml content template to 'plantuml syntax' uml
     # 1. Remove @startuml and @enduml
     uml_content = uml_content.replace("@startuml", "").replace("@enduml", "")
 
     # 2. Prepare jinja template
-    mem_template = Environment(loader=BaseLoader).from_string(uml_content)
+    mem_template = Environment(loader=BaseLoader()).from_string(uml_content)
 
     # 3. Get a new instance of Jinja Helper Functions
     jinja_utils = JinjaFunctions(app, fromdocname, parent_need_id, processed_need_ids)
@@ -211,7 +227,7 @@ def jinja2uml(
         )
 
     # 5. Get data for the jinja processing
-    data = {}
+    data: dict[str, Any] = {}
     # 5.1 Set default config to data
     data.update(**NeedsSphinxConfig(app.config).render_context)
     # 5.2 Set uml() kwargs to data and maybe overwrite default settings
@@ -246,8 +262,12 @@ class JinjaFunctions:
     """
 
     def __init__(
-        self, app: Sphinx, fromdocname, parent_need_id: str, processed_need_ids: dict
-    ):
+        self,
+        app: Sphinx,
+        fromdocname: None | str,
+        parent_need_id: None | str,
+        processed_need_ids: ProcessedNeedsType,
+    ) -> None:
         self.needs = SphinxNeedsData(app.env).get_or_create_needs()
         self.app = app
         self.fromdocname = fromdocname
@@ -258,8 +278,10 @@ def __init__(
             )
         self.processed_need_ids = processed_need_ids
 
-    def need_to_processed_data(self, art: str, key: str, kwargs: dict) -> {}:
-        d = {
+    def need_to_processed_data(
+        self, art: str, key: None | str, kwargs: dict[str, Any]
+    ) -> ProcessedDataType:
+        d: ProcessedDataType = {
             "art": art,
             "key": key,
             "arguments": kwargs,
@@ -267,7 +289,7 @@ def need_to_processed_data(self, art: str, key: str, kwargs: dict) -> {}:
         return d
 
     def append_need_to_processed_needs(
-        self, need_id: str, art: str, key: str, kwargs: dict
+        self, need_id: str, art: str, key: None | str, kwargs: dict[str, Any]
     ) -> None:
         data = self.need_to_processed_data(art=art, key=key, kwargs=kwargs)
         if need_id not in self.processed_need_ids:
@@ -275,7 +297,9 @@ def append_need_to_processed_needs(
         if data not in self.processed_need_ids[need_id]:
             self.processed_need_ids[need_id].append(data)
 
-    def append_needs_to_processed_needs(self, processed_needs_data: dict) -> None:
+    def append_needs_to_processed_needs(
+        self, processed_needs_data: ProcessedNeedsType
+    ) -> None:
         for k, v in processed_needs_data.items():
             if k not in self.processed_need_ids:
                 self.processed_need_ids[k] = []
@@ -284,17 +308,17 @@ def append_needs_to_processed_needs(self, processed_needs_data: dict) -> None:
                     self.processed_need_ids[k].append(d)
 
     def data_in_processed_data(
-        self, need_id: str, art: str, key: str, kwargs: dict
+        self, need_id: str, art: str, key: str, kwargs: dict[str, Any]
     ) -> bool:
         data = self.need_to_processed_data(art=art, key=key, kwargs=kwargs)
         return (need_id in self.processed_need_ids) and (
             data in self.processed_need_ids[need_id]
         )
 
-    def get_processed_need_ids(self) -> {}:
+    def get_processed_need_ids(self) -> ProcessedNeedsType:
         return self.processed_need_ids
 
-    def uml_from_need(self, need_id: str, key: str = "diagram", **kwargs) -> str:
+    def uml_from_need(self, need_id: str, key: str = "diagram", **kwargs: Any) -> str:
         if need_id not in self.needs:
             raise NeedumlException(
                 f"Jinja function uml() is called with undefined need_id: '{need_id}'."
@@ -337,7 +361,7 @@ def uml_from_need(self, need_id: str, key: str = "diagram", **kwargs) -> str:
 
         return uml
 
-    def flow(self, need_id) -> str:
+    def flow(self, need_id: str) -> str:
         if need_id not in self.needs:
             raise NeedumlException(
                 f"Jinja function flow is called with undefined need_id: '{need_id}'."
@@ -368,7 +392,9 @@ def flow(self, need_id) -> str:
 
         return need_uml
 
-    def ref(self, need_id: str, option: str = None, text: str = None) -> str:
+    def ref(
+        self, need_id: str, option: None | str = None, text: None | str = None
+    ) -> str:
         if need_id not in self.needs:
             raise NeedumlException(
                 f"Jinja function ref is called with undefined need_id: '{need_id}'."
@@ -388,7 +414,7 @@ def ref(self, need_id: str, option: str = None, text: str = None) -> str:
 
         return need_uml
 
-    def filter(self, filter_string):
+    def filter(self, filter_string: str) -> list[NeedsInfoType]:
         """
         Return a list of found needs that pass the given filter string.
         """
@@ -398,7 +424,7 @@ def filter(self, filter_string):
             list(self.needs.values()), needs_config, filter_string=filter_string
         )
 
-    def imports(self, *args):
+    def imports(self, *args: str) -> str:
         if not self.parent_need_id:
             raise NeedumlException(
                 "Jinja function 'import()' is not supported in needuml directive."
@@ -408,8 +434,14 @@ def imports(self, *args):
         uml_ids = []
         for option_name in args:
             # check if link option_name exists in current need object
-            if option_name in need_info and need_info[option_name]:
-                for id in need_info[option_name]:
+            if option_value := need_info.get(option_name):
+                try:
+                    iterable_value = list(option_value)  # type: ignore
+                except TypeError:
+                    raise NeedumlException(
+                        f"Option value for {option_name!r} is not iterable."
+                    )
+                for id in iterable_value:
                     uml_ids.append(id)
         umls = ""
         if uml_ids:
@@ -420,7 +452,7 @@ def imports(self, *args):
                 umls += local_uml_from_need
         return umls
 
-    def need(self):
+    def need(self) -> NeedsInfoType:
         if not self.parent_need_id:
             raise NeedumlException(
                 "Jinja function 'need()' is not supported in needuml directive."