diff --git a/lib/decentralised_book_index/metadata/book.ex b/lib/decentralised_book_index/metadata/book.ex
index 07bc797..387d97b 100644
--- a/lib/decentralised_book_index/metadata/book.ex
+++ b/lib/decentralised_book_index/metadata/book.ex
@@ -204,7 +204,7 @@ defmodule DecentralisedBookIndex.Metadata.Book do
       description "Return a list of Books, optionally filtering by BookId."
 
       argument :type, :string, allow_nil?: false
-      argument :bid, :string, allow_nil?: false
+      argument :bid, :string, allow_nil?: true
 
       filter expr(exists(bids, type == ^arg(:type) and contains(bid, ^arg(:bid))))
 
diff --git a/test/decentralised_book_index_web/live/book_live/index_test.exs b/test/decentralised_book_index_web/live/book_live/index_test.exs
new file mode 100644
index 0000000..deca49c
--- /dev/null
+++ b/test/decentralised_book_index_web/live/book_live/index_test.exs
@@ -0,0 +1,45 @@
+defmodule DecentralisedBookIndexWeb.Live.BookLive.IndexTest do
+  use DecentralisedBookIndexWeb.LiveCase, async: true
+
+  describe "Search by bid" do
+    setup do
+      %{
+        modes: [
+          "isbn",
+          "isbn13",
+          "asin"
+        ],
+        books:
+          for _ <- 1..5 do
+            generate(book())
+          end
+      }
+    end
+
+    test "can search by an empty bid", %{conn: conn, modes: modes} do
+      for mode <- modes do
+        {:ok, _view, html} =
+          conn
+          |> live("/books?search_mode=#{mode}")
+
+        assert html =~ "Listing Books"
+        assert html =~ "No Books"
+      end
+    end
+
+    test "can search by a bid", %{conn: conn, modes: modes, books: books} do
+      [book | others] = books
+
+      for %{type: type, bid: bid} <- book.bids do
+        {:ok, view, html} =
+          conn
+          |> live("/books?query=#{bid}&search_mode=#{type}")
+
+        html = render(view)
+
+        assert html =~ book.title
+        refute html =~ "No Books"
+      end
+    end
+  end
+end