diff --git a/tracetools_launch/setup.cfg b/tracetools_launch/setup.cfg
index 622fcba0..86ce32d0 100644
--- a/tracetools_launch/setup.cfg
+++ b/tracetools_launch/setup.cfg
@@ -2,3 +2,5 @@
 script_dir=$base/lib/tracetools_launch
 [install]
 install_scripts=$base/lib/tracetools_launch
+[mypy]
+warn-unused-ignores = True
diff --git a/tracetools_launch/tracetools_launch/action.py b/tracetools_launch/tracetools_launch/action.py
index ffc38ecb..97ddeaf5 100644
--- a/tracetools_launch/tracetools_launch/action.py
+++ b/tracetools_launch/tracetools_launch/action.py
@@ -21,6 +21,7 @@
 from typing import Dict
 from typing import Iterable
 from typing import List
+from typing import Mapping
 from typing import Optional
 from typing import Text
 from typing import Union
@@ -34,6 +35,7 @@
 from launch.frontend import Parser
 from launch.launch_context import LaunchContext
 from launch.some_substitutions_type import SomeSubstitutionsType
+from launch.substitution import Substitution
 from launch.substitutions import TextSubstitution
 from launch.utilities import normalize_to_list_of_substitutions
 from launch.utilities import perform_substitutions
@@ -159,59 +161,62 @@ def __init__(
         self._base_path = base_path \
             if base_path is None else normalize_to_list_of_substitutions(base_path)
         self._append_trace = append_trace
-        self._trace_directory = None
+        self._trace_directory: Optional[str] = None
         self._events_ust = [normalize_to_list_of_substitutions(x) for x in events_ust]
         self._events_kernel = [normalize_to_list_of_substitutions(x) for x in events_kernel]
         self._syscalls = [normalize_to_list_of_substitutions(x) for x in syscalls]
-        self._context_fields = \
+        self._context_fields = (
             {
                 domain: [normalize_to_list_of_substitutions(field) for field in fields]
                 for domain, fields in context_fields.items()
-            } \
-            if isinstance(context_fields, dict) \
+            }
+            if isinstance(context_fields, dict)
             else [normalize_to_list_of_substitutions(field) for field in context_fields]
-        self._ld_preload_actions: List[LdPreload] = []
+        )
+        self._ld_preload_actions: List[Action] = []
         self._subbuffer_size_ust = subbuffer_size_ust
         self._subbuffer_size_kernel = subbuffer_size_kernel
 
     @property
-    def session_name(self):
+    def session_name(self) -> List[Substitution]:
         return self._session_name
 
     @property
-    def base_path(self):
+    def base_path(self) -> Optional[List[Substitution]]:
         return self._base_path
 
     @property
-    def append_trace(self):
+    def append_trace(self) -> bool:
         return self._append_trace
 
     @property
-    def trace_directory(self):
+    def trace_directory(self) -> Optional[str]:
         return self._trace_directory
 
     @property
-    def events_ust(self):
+    def events_ust(self) -> Iterable[List[Substitution]]:
         return self._events_ust
 
     @property
-    def events_kernel(self):
+    def events_kernel(self) -> Iterable[List[Substitution]]:
         return self._events_kernel
 
     @property
-    def syscalls(self):
+    def syscalls(self) -> Iterable[List[Substitution]]:
         return self._syscalls
 
     @property
-    def context_fields(self):
+    def context_fields(
+        self,
+    ) -> Union[Mapping[str, Iterable[List[Substitution]]], Iterable[List[Substitution]]]:
         return self._context_fields
 
     @property
-    def subbuffer_size_ust(self):
+    def subbuffer_size_ust(self) -> int:
         return self._subbuffer_size_ust
 
     @property
-    def subbuffer_size_kernel(self):
+    def subbuffer_size_kernel(self) -> int:
         return self._subbuffer_size_kernel
 
     @classmethod
@@ -459,7 +464,7 @@ def _destroy(self, event: Event, context: LaunchContext) -> None:
         self._logger.debug(f'Finalizing tracing session: {self._session_name}')
         lttng.lttng_fini(session_name=self._session_name)
 
-    def __repr__(self):
+    def __repr__(self) -> Text:
         return (
             'Trace('
             f'session_name={self._session_name}, '
diff --git a/tracetools_launch/tracetools_launch/actions/ld_preload.py b/tracetools_launch/tracetools_launch/actions/ld_preload.py
index f2b53b85..463090cd 100644
--- a/tracetools_launch/tracetools_launch/actions/ld_preload.py
+++ b/tracetools_launch/tracetools_launch/actions/ld_preload.py
@@ -19,6 +19,7 @@
 import subprocess
 from typing import List
 from typing import Optional
+from typing import Text
 
 from launch import logging
 from launch.action import Action
@@ -45,7 +46,7 @@ def __init__(
         """
         super().__init__(**kwargs)
         self._lib_name = lib_name
-        self._env_action = None
+        self._env_action: Optional[Action] = None
         # Try to find lib
         self._lib_path = self.get_shared_lib_path(self._lib_name)
         # And create action if found
@@ -65,9 +66,19 @@ def lib_name(self) -> str:
 
     @property
     def lib_path(self) -> Optional[str]:
+        """
+        Get the resolved shared lib path, if found.
+
+        :return: the full path to the shared lib if found, or `None` if not found
+        """
         return self._lib_path
 
     def lib_found(self) -> bool:
+        """
+        Check if the shared lib was found.
+
+        :return: `True` if the shared lib was found, or `False` if not found
+        """
         return self._env_action is not None
 
     def execute(self, context: LaunchContext) -> Optional[List[Action]]:
@@ -113,7 +124,7 @@ def get_shared_lib_path(cls, lib_name: str) -> Optional[str]:
         shared_lib = shared_lib_paths[0]
         return shared_lib
 
-    def __repr__(self):
+    def __repr__(self) -> Text:
         return (
             'LdPreload('
             f'lib_name={self._lib_name}, '
diff --git a/tracetools_read/setup.cfg b/tracetools_read/setup.cfg
index de27ea5f..dae89709 100644
--- a/tracetools_read/setup.cfg
+++ b/tracetools_read/setup.cfg
@@ -2,3 +2,5 @@
 script_dir=$base/lib/tracetools_read
 [install]
 install_scripts=$base/lib/tracetools_read
+[mypy]
+warn-unused-ignores = True
diff --git a/tracetools_test/setup.cfg b/tracetools_test/setup.cfg
index 24097e96..2b1f68c0 100644
--- a/tracetools_test/setup.cfg
+++ b/tracetools_test/setup.cfg
@@ -2,3 +2,5 @@
 script_dir=$base/lib/tracetools_test
 [install]
 install_scripts=$base/lib/tracetools_test
+[mypy]
+warn-unused-ignores = True
diff --git a/tracetools_test/tracetools_test/case.py b/tracetools_test/tracetools_test/case.py
index c6681fc4..0ca4393b 100644
--- a/tracetools_test/tracetools_test/case.py
+++ b/tracetools_test/tracetools_test/case.py
@@ -86,7 +86,7 @@ def __init__(
         self._additional_actions = additional_actions or []
         self._namespace = namespace
 
-    def setUp(self):
+    def setUp(self) -> None:
         # Get timestamp before trace (ns)
         timestamp_before = int(time.time() * 1000000000.0)
 
@@ -133,7 +133,7 @@ def setUp(self):
         # Check that the launched nodes are present as processes
         self.assertProcessNamesExist(self._nodes)
 
-    def tearDown(self):
+    def tearDown(self) -> None:
         if not os.environ.get(self.ENV_VAR_DEBUG, None):
             cleanup_trace(self._full_path)
 
diff --git a/tracetools_trace/setup.cfg b/tracetools_trace/setup.cfg
index 855f7636..848d0db3 100644
--- a/tracetools_trace/setup.cfg
+++ b/tracetools_trace/setup.cfg
@@ -2,3 +2,5 @@
 script_dir=$base/lib/tracetools_trace
 [install]
 install_scripts=$base/lib/tracetools_trace
+[mypy]
+warn-unused-ignores = True