diff --git a/pupy/requirements.txt b/pupy/requirements.txt
index fdae9a75..6e516f69 100644
--- a/pupy/requirements.txt
+++ b/pupy/requirements.txt
@@ -1,7 +1,7 @@
 pycryptodome
 pefile 
 pyyaml
-rsa
+rsa==4.0
 netaddr
 ecdsa==0.13
 paramiko==2.0.2