diff --git a/manifests/init.pp b/manifests/init.pp
index 4462f9cb..08e95b1a 100644
--- a/manifests/init.pp
+++ b/manifests/init.pp
@@ -134,7 +134,7 @@
   Hash                                          $global_options       = $haproxy::params::global_options,
   Hash                                          $defaults_options     = $haproxy::params::defaults_options,
   Boolean                                       $merge_options        = $haproxy::params::merge_options,
-  Optional[Array[String]]                       $install_options      = undef,
+  Array[String[1]]                              $install_options      = [],
   Optional[String]                              $restart_command      = undef,
   Optional[String]                              $custom_fragment      = undef,
   Stdlib::Absolutepath                          $config_dir           = $haproxy::params::config_dir,