diff --git a/src/rapids_dependency_file_generator/_cli.py b/src/rapids_dependency_file_generator/_cli.py
index 3ff424c..c8babaa 100644
--- a/src/rapids_dependency_file_generator/_cli.py
+++ b/src/rapids_dependency_file_generator/_cli.py
@@ -130,7 +130,7 @@ def generate_matrix(matrix_arg):
     return matrix
 
 
-def main(argv=None):
+def main(argv=None) -> None:
     args = validate_args(argv)
 
     parsed_config = load_config_from_file(args.config)
diff --git a/src/rapids_dependency_file_generator/_rapids_dependency_file_generator.py b/src/rapids_dependency_file_generator/_rapids_dependency_file_generator.py
index 02f48fc..e45116d 100644
--- a/src/rapids_dependency_file_generator/_rapids_dependency_file_generator.py
+++ b/src/rapids_dependency_file_generator/_rapids_dependency_file_generator.py
@@ -68,7 +68,7 @@ def dedupe(
         return sorted(string_deps)
 
 
-def grid(gridspec: dict[str, list[str]]) -> Generator[dict[str, str]]:
+def grid(gridspec: dict[str, list[str]]) -> Generator[dict[str, str], None, None]:
     """Yield the Cartesian product of a `dict` of iterables.
 
     The input ``gridspec`` is a dictionary whose keys correspond to
@@ -281,7 +281,7 @@ def get_output_dir(*, file_type: _config.Output, config_file_path: os.PathLike,
     return os.path.join(*path)
 
 
-def should_use_specific_entry(matrix_combo: dict[str, str], specific_entry_matrix: dict[str, str]):
+def should_use_specific_entry(matrix_combo: dict[str, str], specific_entry_matrix: dict[str, str]) -> bool:
     """Check if an entry should be used.
 
     Dependencies listed in the [dependencies.$DEPENDENCY_GROUP.specific]
diff --git a/src/rapids_dependency_file_generator/_rapids_dependency_file_validator.py b/src/rapids_dependency_file_generator/_rapids_dependency_file_validator.py
index a9a8aab..1327c4c 100644
--- a/src/rapids_dependency_file_generator/_rapids_dependency_file_validator.py
+++ b/src/rapids_dependency_file_generator/_rapids_dependency_file_validator.py
@@ -11,7 +11,7 @@
 SCHEMA = json.loads(importlib.resources.files(__package__).joinpath("schema.json").read_bytes())
 
 
-def validate_dependencies(dependencies):
+def validate_dependencies(dependencies) -> None:
     """Validate a dictionary against the dependencies.yaml spec.
 
     Parameters