diff --git a/metadata-ingestion/setup.cfg b/metadata-ingestion/setup.cfg
index 2467c61983e5d..f1cc51e5d4495 100644
--- a/metadata-ingestion/setup.cfg
+++ b/metadata-ingestion/setup.cfg
@@ -26,6 +26,7 @@ plugins =
     pydantic.mypy
 exclude = ^(venv|build|dist)/
 ignore_missing_imports = yes
+namespace_packages = no
 strict_optional = yes
 check_untyped_defs = yes
 disallow_incomplete_defs = yes
diff --git a/metadata-ingestion/setup.py b/metadata-ingestion/setup.py
index c81ac28577ff3..8fe81dcab36d7 100644
--- a/metadata-ingestion/setup.py
+++ b/metadata-ingestion/setup.py
@@ -373,7 +373,10 @@ def get_long_description():
     "flake8>=3.8.3",
     "flake8-tidy-imports>=4.3.0",
     "isort>=5.7.0",
-    "mypy>=0.981",
+    # mypy 0.990 enables namespace packages by default and sets
+    # no implicit optional to True.
+    # FIXME: Enable mypy 0.990 when our codebase is fixed.
+    "mypy>=0.981,<0.990",
     # pydantic 1.8.2 is incompatible with mypy 0.910.
     # See https://github.com/samuelcolvin/pydantic/pull/3175#issuecomment-995382910.
     # Restricting top version to <1.10 until we can fix our types.