diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index f6d5ddf4c985..9d91544e59be 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -3447,7 +3447,7 @@ in {
   cryptography = buildPythonPackage rec {
     # also bump cryptography_vectors
     pname = "cryptography";
-    name = "${pname}${version}";
+    name = "${pname}-${version}";
     version = "1.8.1";
 
     src = fetchPypi {