diff --git a/elements/horizon/install.d/horizon-source-install/100-horizon b/elements/horizon/install.d/horizon-source-install/100-horizon
index cd06d9da2..05b66545f 100755
--- a/elements/horizon/install.d/horizon-source-install/100-horizon
+++ b/elements/horizon/install.d/horizon-source-install/100-horizon
@@ -1,7 +1,7 @@
 #!/bin/bash
 set -eux
 
-install-packages libapache2-mod-wsgi
+install-packages libapache2-mod-wsgi libssl-dev libffi-dev
 
 if [ -d /etc/apache2 ]; then
     ln -s /etc/httpd/conf.d/horizon.conf /etc/apache2/sites-available/horizon.conf