diff --git a/lib/wabanex_web/schema/types/custom/date_range.ex b/lib/wabanex_web/schema/types/custom/date_range.ex
index 45e2dd3..ebb1e40 100644
--- a/lib/wabanex_web/schema/types/custom/date_range.ex
+++ b/lib/wabanex_web/schema/types/custom/date_range.ex
@@ -17,10 +17,11 @@ defmodule WabanexWeb.Schema.Types.Custom.DateRange do
   end
 
   @spec serialize_range(PgRanges.DateRange.t()) :: String.t()
-  @spec serialize_range(list(DateTime.t() | nil)) :: String.t()
+  @spec serialize_range(list(DateTime.t() | nil | atom)) :: String.t()
   defp serialize_range(%PgRanges.DateRange{lower: start_range, upper: end_range}),
     do: serialize_range([start_range, end_range])
 
+  defp serialize_range([start_range, :unbound]), do: serialize_range([start_range, nil])
   defp serialize_range([start_range, nil]), do: "#{Date.to_iso8601(start_range)},"
 
   defp serialize_range([start_range, end_range]),
diff --git a/test/wabanex_web/schema/types/custom/date_range_test.exs b/test/wabanex_web/schema/types/custom/date_range_test.exs
index 2a1cb99..72ab627 100644
--- a/test/wabanex_web/schema/types/custom/date_range_test.exs
+++ b/test/wabanex_web/schema/types/custom/date_range_test.exs
@@ -43,6 +43,9 @@ defmodule WabanexWeb.Schema.Types.Custom.DateRangeTest do
 
       assert {:ok, DateRange.new(~D[1978-12-15], nil)} ==
                parse(:date_range, %Input.String{value: "1978-12-15"})
+
+      assert {:ok, DateRange.new(~D[1978-12-15], :unbound)} ==
+               parse(:date_range, %Input.String{value: "1978-12-15"})
     end
   end
 end