diff --git a/MANIFEST.in b/MANIFEST.in
index 25be1608..67d3851d 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,4 +1,5 @@
 include MANIFEST.in README.rst LICENSE certifi/cacert.pem certifi/py.typed
+recursive-include certifi/tests *
 
 exclude .github/
 recursive-exclude .github