diff --git a/lib/xandra/cluster.ex b/lib/xandra/cluster.ex
index 6aabdb8d..c66f00db 100644
--- a/lib/xandra/cluster.ex
+++ b/lib/xandra/cluster.ex
@@ -329,6 +329,7 @@ defmodule Xandra.Cluster do
   def start_link(options) when is_list(options) do
     {cluster_opts, connection_opts} = Keyword.split(options, @start_link_opts_schema_keys)
     cluster_opts = NimbleOptions.validate!(cluster_opts, @start_link_opts_schema)
+    connection_opts = NimbleOptions.validate!(connection_opts, Xandra.start_link_opts_schema())
     Pool.start_link(cluster_opts, connection_opts)
   end
 
diff --git a/test/xandra/cluster_test.exs b/test/xandra/cluster_test.exs
index ea90b221..47463ed4 100644
--- a/test/xandra/cluster_test.exs
+++ b/test/xandra/cluster_test.exs
@@ -141,6 +141,12 @@ defmodule Xandra.ClusterTest do
         Xandra.Cluster.start_link(nodes: ["example.com:9042"], name: "something something")
       end
     end
+
+    test "raises with an option that is not valid for the cluster and for the conn" do
+      assert_raise NimbleOptions.ValidationError, ~r"unknown options \[:port\]", fn ->
+        Xandra.Cluster.start_link(port: 9042)
+      end
+    end
   end
 
   describe "start_link/1" do
diff --git a/test/xandra_test.exs b/test/xandra_test.exs
index d22fc9be..7d9a788c 100644
--- a/test/xandra_test.exs
+++ b/test/xandra_test.exs
@@ -234,12 +234,12 @@ defmodule XandraTest do
         end)
         |> Enum.map(fn {:ok, result} -> result end)
 
-      # The first and second calls succeeds, but the third call fails because it goes over
+      # The first call succeeds, but the second call fails because it goes over
       # the max concurrent conns.
       assert [
                {1, {:ok, %Xandra.Page{}}},
                {2, {:error, %ConnectionError{reason: :too_many_concurrent_requests} = error}}
-             ] = results
+             ] = Enum.sort_by(results, &elem(&1, 0))
 
       assert Exception.message(error) =~ "this connection has too many requests in flight"
     end