diff --git a/conf/packages b/conf/packages
index b3f38b5e28f..a5cfb855fb2 100644
--- a/conf/packages
+++ b/conf/packages
@@ -1,6 +1,8 @@
 # Please note that this package list currently forms part of the
 # mySociety deployment infrastructure -- please discuss on the
 # mailing list if you want to change it.
+# Note additions to this file will probably need adding to the
+# packages.generic and packages.docker files as well.
 
 make
 g++
diff --git a/conf/packages.generic b/conf/packages.generic
index f31d6200758..dea6a9f7cfb 100644
--- a/conf/packages.generic
+++ b/conf/packages.generic
@@ -16,3 +16,4 @@ libexpat1-dev
 libssl-dev
 zlib1g-dev
 libxml2-dev
+libreadline-dev