diff --git a/MANIFEST.in b/MANIFEST.in
index bd10c4e8..dc42f17a 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -4,4 +4,5 @@ recursive-include tests *
 recursive-include docs *
 recursive-exclude docs/_build *
 recursive-exclude plugins *
+recursive-exclude tests_isolated *
 exclude .github .gitignore azure-pipelines.yml tasks.py