diff --git a/src/cligen/flag.cr b/src/cligen/flag.cr
index c425999..e6b8e71 100644
--- a/src/cligen/flag.cr
+++ b/src/cligen/flag.cr
@@ -74,11 +74,20 @@ module CliGen
         {% elem = T.type_vars.first %}
         {% raise "ERROR : Flag(#{T}) : Error your flag subtype #{elem} must have a to_s method" unless elem.class.has_method? :to_s %}
       {% end %}
+      unless @default.nil?
+        {% if T < Array %}
+          default = "[" + @default.not_nil!.map(&.to_s).join(", ") + "]"
+        {% else %}
+          default = @default.not_nil!.to_s
+        {% end %}
+      else
+        default = nil
+      end
       meta = FlagMeta.new(
         type: {{T.stringify}},
         array: {{ T < Array ? true : false }},
         options: {% if T < Array %} @options.try(&.first.map(&.to_s)) {% else %} @options.try(&.map(&.to_s)) {% end %},
-        default: @default.try(&.to_s),
+        default: default,
         format: @format.try(&.source)
       )
       super(var, short, long, env_var, description, delimiter, meta)
diff --git a/src/cligen/template/cmd_help.ecr b/src/cligen/template/cmd_help.ecr
index 6ee01c9..344802f 100644
--- a/src/cligen/template/cmd_help.ecr
+++ b/src/cligen/template/cmd_help.ecr
@@ -14,7 +14,7 @@ Flags:
   <%- else -%>
     <%- flags = [flag.short,flag.long.strip] -%>
   <%- end -%>
-    <%= "%-#{len}s %s" % [flags.join(","), flag.description.strip] %><%= flag.meta.options.nil? ? "" : " (valid: #{flag.meta.options.not_nil!.join(", ")})" %><%= flag.meta.default.nil? ? "" : " (default: #{flag.meta.default.to_s})" %>
+    <%= "%-#{len}s %s" % [flags.join(","), flag.description.strip] %><%= flag.meta.options.nil? ? "" : " (valid: #{flag.meta.options.not_nil!.join(", ")})" %><%= flag.meta.default.nil? ? "" : " (default: #{flag.meta.default.not_nil!})" %>
   <%- if verbose? -%>
     <%= "%-#{len}s %s" % ["", "Type: #{flag.meta.type}"] %>
     <%= "%-#{len}s %s" % ["", "ENV VAR: #{flag.env_var}"] %>