diff --git a/REFERENCE.md b/REFERENCE.md
index ce9b2f7..b19d818 100644
--- a/REFERENCE.md
+++ b/REFERENCE.md
@@ -78,11 +78,11 @@ The following parameters are available in the `caddy` class:
 
 ##### <a name="-caddy--version"></a>`version`
 
-Data type: `String[1]`
+Data type: `Optional[String[1]]`
 
-Which version is used.
+Which version of caddy to install when install_method is github.
 
-Default value: `'2.0.0'`
+Default value: `undef`
 
 ##### <a name="-caddy--install_method"></a>`install_method`
 
diff --git a/manifests/init.pp b/manifests/init.pp
index 0089bb5..b7b46d2 100644
--- a/manifests/init.pp
+++ b/manifests/init.pp
@@ -16,7 +16,7 @@
 #   }
 #
 # @param version
-#   Which version is used.
+#   Which version of caddy to install when install_method is github.
 #
 # @param install_method
 #   Which source is used.
@@ -76,7 +76,7 @@
 #   Whether the process and all its children can gain new privileges through execve().
 #
 class caddy (
-  String[1]                      $version                         = '2.0.0',
+  Optional[String[1]]            $version                         = undef,
   Optional[Enum['github']]       $install_method                  = undef,
   Stdlib::Absolutepath           $install_path                    = '/opt/caddy',
   String[1]                      $caddy_user                      = 'caddy',
diff --git a/manifests/install.pp b/manifests/install.pp
index cfa14ba..4819059 100644
--- a/manifests/install.pp
+++ b/manifests/install.pp
@@ -9,6 +9,10 @@
   $bin_file = "${caddy::install_path}/caddy"
 
   if $caddy::install_method == 'github' {
+    if !$caddy::version {
+      fail('caddy::version must be set when caddy::install_method is github')
+    }
+
     $caddy_url    = 'https://github.com/caddyserver/caddy/releases/download'
     $caddy_dl_url = "${caddy_url}/v${caddy::version}/caddy_${caddy::version}_linux_${caddy::arch}.tar.gz"
     $caddy_dl_dir = "/var/cache/caddy_${caddy::version}_linux_${$caddy::arch}.tar.gz"
@@ -37,6 +41,10 @@
 
     $caddy_source = "/var/cache/caddy-${caddy::version}/caddy"
   } else {
+    if $caddy::version {
+      fail('caddy::version can only be set when caddy::install_method is github')
+    }
+
     $caddy_url    = 'https://caddyserver.com/api/download'
     $caddy_dl_url = "${caddy_url}?os=linux&arch=${caddy::arch}&plugins=${caddy::caddy_features}&license=${caddy::caddy_license}&telemetry=${caddy::caddy_telemetry}"