diff --git a/pyproject.toml b/pyproject.toml
index 87955f5aed80f1fe68ba5ad636305ff1ee6395c9..e416476e13d746f091daa47b6f851e0749f42ba8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -46,5 +46,6 @@ line-length=100
 
 [tool.mypy]
 check_untyped_defs = true
+disallow_incomplete_defs = true
 disallow_untyped_calls = true
 disallow_untyped_decorators = true