diff --git a/MANIFEST.in b/MANIFEST.in
index 987b96c292..df46685ecd 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -8,6 +8,7 @@ include LICENSE.txt
 recursive-exclude * __pycache__
 recursive-exclude * *.py[co]
 recursive-include act/plotting *.txt
+recursive-include act/tests *
 
 recursive-include docs *.rst conf.py Makefile make.bat
 
diff --git a/pyproject.toml b/pyproject.toml
index 9ed57e15fd..06353c6682 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -5,4 +5,4 @@ skip-string-normalization = true
 ignore = ["act/io/arm.py"]
 
 [tool.check-manifest]
-ignore = ["docs/*", "tests/*", "ci/*"]
+ignore = ["docs/*", "ci/*"]