diff --git a/modoboa_installer/scripts/modoboa.py b/modoboa_installer/scripts/modoboa.py
index 2fc4bc2..4eec27d 100644
--- a/modoboa_installer/scripts/modoboa.py
+++ b/modoboa_installer/scripts/modoboa.py
@@ -20,7 +20,7 @@ class Modoboa(base.Installer):
     no_daemon = True
     packages = [
         "build-essential", "python-dev", "libxml2-dev", "libxslt-dev",
-        "libjpeg-dev", "librrd-dev", "rrdtool", "libffi-dev"]
+        "libjpeg-dev", "librrd-dev", "rrdtool", "libffi-dev", "cron"]
     config_files = [
         "crontab=/etc/cron.d/modoboa",
         "sudoers=/etc/sudoers.d/modoboa",
diff --git a/modoboa_installer/utils.py b/modoboa_installer/utils.py
index 7f6be90..4986eff 100644
--- a/modoboa_installer/utils.py
+++ b/modoboa_installer/utils.py
@@ -86,8 +86,10 @@ def install_system_package(name, update=False):
     exec_cmd("apt-get install --quiet --assume-yes {}".format(name))
 
 
-def install_system_packages(names):
+def install_system_packages(names, update=False):
     """Install some packages system-wide."""
+    if update:
+        exec_cmd("apt-get update --quiet")
     exec_cmd("apt-get install --quiet --assume-yes {}".format(" ".join(names)))