diff --git a/pyproject.toml b/pyproject.toml
index 6d467460..49ab7723 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -8,6 +8,7 @@ plugins = "numpy.typing.mypy_plugin"
 ignore_missing_imports = true
 files = "dedupe"
 check_untyped_defs = true
+show_error_codes = true
 
 [tool.pytest.ini_options]
 minversion = "7.1"