diff --git a/tracetools_analysis/tracetools_analysis/convert.py b/tracetools_analysis/tracetools_analysis/convert.py
index 75d87a8..80d92ae 100644
--- a/tracetools_analysis/tracetools_analysis/convert.py
+++ b/tracetools_analysis/tracetools_analysis/convert.py
@@ -39,7 +39,7 @@ def add_args(parser: argparse.ArgumentParser) -> None:
         'under $trace_directory (default: %(default)s)')
 
 
-def parse_args():
+def parse_args() -> argparse.Namespace:
     parser = argparse.ArgumentParser(
         description='Convert trace data to a file.')
     add_args(parser)
diff --git a/tracetools_analysis/tracetools_analysis/process.py b/tracetools_analysis/tracetools_analysis/process.py
index ca83445..1cfcbbf 100644
--- a/tracetools_analysis/tracetools_analysis/process.py
+++ b/tracetools_analysis/tracetools_analysis/process.py
@@ -42,7 +42,7 @@ def add_args(parser: argparse.ArgumentParser) -> None:
         help='hide/suppress results from being printed')
 
 
-def parse_args():
+def parse_args() -> argparse.Namespace:
     parser = argparse.ArgumentParser(description='Process a file converted from a trace '
                                                  'directory and output model data.')
     add_args(parser)