diff --git a/tests/acceptance/proxy_tests.rb b/tests/acceptance/proxy_tests.rb
index e4030a4..37b5a9d 100644
--- a/tests/acceptance/proxy_tests.rb
+++ b/tests/acceptance/proxy_tests.rb
@@ -4,7 +4,7 @@ require 'flexnbd/fake_dest'
 
 module ProxyTests
   def b
-    String.new("\xFF", encoding: "BINARY")
+    "\xFF".b
   end
 
   def with_proxied_client( override_size = nil )
diff --git a/tests/acceptance/test_serve_mode.rb b/tests/acceptance/test_serve_mode.rb
index bbf6025..6cf383b 100644
--- a/tests/acceptance/test_serve_mode.rb
+++ b/tests/acceptance/test_serve_mode.rb
@@ -6,7 +6,7 @@ class TestServeMode < Test::Unit::TestCase
 
   def setup
     super
-    @b = String.new("\xFF", encoding: "BINARY")
+    @b = "\xFF".b
     @env = Environment.new
     @env.writefile1( "0" )
     @env.serve1