diff --git a/Changelog.md b/Changelog.md
index 00db869..8d8e439 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,6 +1,7 @@
 ## 0.9.11 (not yet released)
 
  * The `ca-certificates` package is now installed by default. This is because we include `apt-transport-https`, but Ubuntu 14.04 no longer installs `ca-certificates` by default anymore. Closes GH-73.
+ * `add-apt-repository` is now installed by default. Closes GH-74.
 
 ## 0.9.10 (release date: 2014-05-12)
 
diff --git a/image/prepare.sh b/image/prepare.sh
index b15c334..ef49700 100755
--- a/image/prepare.sh
+++ b/image/prepare.sh
@@ -33,6 +33,9 @@ ln -sf /bin/true /usr/bin/ischroot
 ## Install HTTPS support for APT.
 $minimal_apt_get_install apt-transport-https ca-certificates
 
+## Install add-apt-repository
+$minimal_apt_get_install software-properties-common
+
 ## Upgrade all packages.
 apt-get dist-upgrade -y --no-install-recommends