diff --git a/test/ruby/envutil.rb b/test/ruby/envutil.rb
index 57d2d11f6b..41ba7ecf1b 100644
--- a/test/ruby/envutil.rb
+++ b/test/ruby/envutil.rb
@@ -285,8 +285,11 @@ module Test
           file ||= loc.path
           line ||= loc.lineno
         end
+        line -= 2
         src = <<eom
-  require #{__dir__.dump}'/envutil';include Test::Unit::Assertions;begin;#{src}
+# -*- coding: #{src.encoding}; -*-
+  require #{__dir__.dump}'/envutil';include Test::Unit::Assertions;begin
+#{src}
   ensure
     puts [Marshal.dump($!)].pack('m'), "assertions=\#{self._assertions}"
   end
diff --git a/test/ruby/test_require.rb b/test/ruby/test_require.rb
index 77b2a6fbf4..0351939216 100644
--- a/test/ruby/test_require.rb
+++ b/test/ruby/test_require.rb
@@ -71,13 +71,16 @@ class TestRequire < Test::Unit::TestCase
       end
       Dir.mkdir(File.dirname(require_path))
       open(require_path, "wb") {}
-      assert_in_out_err([], <<-INPUT, %w(:ok), [], bug8165)
-        # coding: #{encoding}
+      assert_separately(%w[--disable=gems], <<-INPUT)
         # leave paths for require encoding objects
+        bug = "#{bug8165} require #{encoding} path"
+        path = "#{require_path}"
         enc_path = Regexp.new(Regexp.escape(RUBY_PLATFORM))
         $:.replace([IO::NULL] + $:.reject {|path| enc_path !~ path})
-        p :ok if require '#{require_path}'
-        p :ng if require '#{require_path}'
+        assert_nothing_raised(LoadError, bug) {
+          assert(require(path), bug)
+          assert(!require(path), bug)
+        }
       INPUT
     }
   end