diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index 9ce05e93fd..29903e9d64 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -1827,7 +1827,7 @@ class TestIO < Test::Unit::TestCase
     end)
   end
 
-  def test_each_byte
+  def test_each_byte2
     pipe(proc do |w|
       w.binmode
       w.puts "foo"
@@ -1846,7 +1846,7 @@ class TestIO < Test::Unit::TestCase
     end)
   end
 
-  def test_each_char
+  def test_each_char2
     pipe(proc do |w|
       w.puts "foo"
       w.puts "bar"