diff --git a/lib/yamatanooroti/windows.rb b/lib/yamatanooroti/windows.rb
index 7cc7343..d4231be 100644
--- a/lib/yamatanooroti/windows.rb
+++ b/lib/yamatanooroti/windows.rb
@@ -519,42 +519,70 @@ def result
     @result || retrieve_screen
   end
 
+  private def assert_screen_with_proc(check_proc, assert_block, convert_proc = :itself.to_proc)
+    retry_until = Time.now + @timeout
+    while Time.now < retry_until
+      #break unless try_sync
+
+      break if check_proc.call(convert_proc.call(result))
+      sleep @wait
+    end
+    sleep @wait
+    assert_block.call(convert_proc.call(result))
+  end
+
   def assert_screen(expected_lines, message = nil)
-    actual_lines = result
-    actual_string = actual_lines.join("\n").sub(/\n*\z/, "\n")
+    lines_to_string = ->(lines) { lines.join("\n").sub(/\n*\z/, "\n") }
     case expected_lines
     when Array
-      assert_equal(expected_lines, actual_lines, message)
+      assert_screen_with_proc(
+        ->(a) { expected_lines == a },
+        ->(a) { assert_equal(expected_lines, a, message) }
+      )
     when String
-      assert_equal(expected_lines, actual_string, message)
+      assert_screen_with_proc(
+        ->(a) { expected_lines == a },
+        ->(a) { assert_equal(expected_lines, a, message) },
+        lines_to_string
+      )
     when Regexp
-      assert_match(expected_lines, actual_string, message)
+      assert_screen_with_proc(
+        ->(a) { expected_lines.match?(a) },
+        ->(a) { assert_match(expected_lines, a, message) },
+        lines_to_string
+      )
     end
   end
 
-  def start_terminal(height, width, command, wait: 1, startup_message: nil)
-    @height = height
-    @width = width
+  def start_terminal(height, width, command, wait: 0.2, timeout: 2, startup_message: nil)
+    @timeout = timeout
     @wait = wait
     @result = nil
+
+    @height = height
+    @width = width
     setup_console(height, width)
     launch(command.map{ |c| quote_command_arg(c) }.join(' '))
+
     case startup_message
     when String
-      check_startup_message = ->(message) {
-        message.start_with?(
-          startup_message.each_char.each_slice(width).map(&:join).join("\0").gsub(/ *\0/, "\n")
-        )
-      }
+      wait_startup_message { |message| message.start_with?(startup_message) }
     when Regexp
-      check_startup_message = ->(message) { startup_message.match?(message) }
+      wait_startup_message { |message| startup_message.match?(message) }
     end
-    if check_startup_message
-      loop do
-        screen = retrieve_screen.join("\n").sub(/\n*\z/, "\n")
-        break if check_startup_message.(screen)
-        sleep @wait
+  end
+
+  private def wait_startup_message
+    wait_until = Time.now + @timeout
+    chunks = +''
+    loop do
+      wait = wait_until - Time.now
+      if wait.negative?
+        raise "Startup message didn't arrive within timeout: #{chunks.inspect}"
       end
+
+      chunks = retrieve_screen.join("\n").sub(/\n*\z/, "\n")
+      break if yield chunks
     end
   end
 end