diff --git a/python/MANIFEST.in b/python/MANIFEST.in
index 0b7433d..6c93d64 100644
--- a/python/MANIFEST.in
+++ b/python/MANIFEST.in
@@ -1,6 +1,7 @@
 include stan/unix/*.stan
 include stan/win/*.stan
 include LICENSE
+include requirements.txt
 
 # Ensure in-place built models do not get included in the source dist.
 prune fbprophet/stan_model