diff --git a/lib/wallaby/session_store.ex b/lib/wallaby/session_store.ex
index f666b3fc..7f5a0f59 100644
--- a/lib/wallaby/session_store.ex
+++ b/lib/wallaby/session_store.ex
@@ -36,16 +36,18 @@ defmodule Wallaby.SessionStore do
     Process.flag(:trap_exit, true)
     tid = :ets.new(name, opts)
 
-    Application.ensure_all_started(:ex_unit)
-
-    ExUnit.after_suite(fn _ ->
-      try do
-        :ets.tab2list(tid)
-        |> Enum.each(&delete_sessions/1)
-      rescue
-        _ -> nil
-      end
-    end)
+    if Code.ensure_loaded?(ExUnit) do
+      Application.ensure_all_started(:ex_unit)
+
+      ExUnit.after_suite(fn _ ->
+        try do
+          :ets.tab2list(tid)
+          |> Enum.each(&delete_sessions/1)
+        rescue
+          _ -> nil
+        end
+      end)
+    end
 
     {:ok, %{ets_table: tid}}
   end
diff --git a/lib/wallaby/webdriver_client.ex b/lib/wallaby/webdriver_client.ex
index 92adf7d6..abbe5785 100644
--- a/lib/wallaby/webdriver_client.ex
+++ b/lib/wallaby/webdriver_client.ex
@@ -23,7 +23,13 @@ defmodule Wallaby.WebdriverClient do
   def create_session(base_url, capabilities) do
     params = %{desiredCapabilities: capabilities}
 
-    request(:post, "#{base_url}session", params)
+    case request(:post, "#{base_url}session", params) do
+      {:ok, %{"status" => status} = nonzero_status_response} when status != 0 ->
+        {:error, nonzero_status_response}
+
+      response ->
+        response
+    end
   end
 
   @doc """