diff --git a/MANIFEST.in b/MANIFEST.in
index cf90df493..8d89f48a2 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -2,6 +2,7 @@ include LICENSE
 include README.rst
 include pyaerocom_env.yml
 recursive-include pyaerocom/data *
+recursive-include tests/ *
 
 prune docs/_build
 prune build