diff --git a/src/e3/testsuite/report/display.py b/src/e3/testsuite/report/display.py
index c070188..01a11ca 100644
--- a/src/e3/testsuite/report/display.py
+++ b/src/e3/testsuite/report/display.py
@@ -456,7 +456,7 @@ def display_failures(
         )
 
 
-def main(argv: Optional[List[str]] = None) -> None:
+def main(argv: Optional[List[str]] = None) -> int:
     args = args_parser.parse_args(argv)
     new_index = ReportIndex.read(args.report)
     old_index = (