diff --git a/ext/-test-/ensure_and_callcc/ensure_and_callcc.c b/ext/-test-/ensure_and_callcc/ensure_and_callcc.c
new file mode 100644
index 0000000000..c098a725eb
--- /dev/null
+++ b/ext/-test-/ensure_and_callcc/ensure_and_callcc.c
@@ -0,0 +1,39 @@
+#include "ruby.h"
+
+struct require_data {
+    VALUE obj;
+    VALUE fname;
+};
+
+static VALUE
+call_require(VALUE arg)
+{
+    struct require_data *data = (struct require_data *)arg;
+    rb_f_require(data->obj, data->fname);
+    return Qnil;
+}
+
+static VALUE
+call_ensure(VALUE _)
+{
+    VALUE v = rb_gv_get("$ensure_called");
+    int called = FIX2INT(v) + 1;
+    rb_gv_set("$ensure_called", INT2FIX(called));
+    return Qnil;
+}
+
+static VALUE
+require_with_ensure(VALUE self, VALUE fname)
+{
+    struct require_data data = {
+        .obj = self,
+        .fname = fname
+    };
+    return rb_ensure(call_require, (VALUE)&data, call_ensure, Qnil);
+}
+
+void
+Init_ensure_and_callcc(void)
+{
+    rb_define_method(rb_mKernel, "require_with_ensure", require_with_ensure, 1);
+}
diff --git a/ext/-test-/ensure_and_callcc/extconf.rb b/ext/-test-/ensure_and_callcc/extconf.rb
new file mode 100644
index 0000000000..123b80b8d0
--- /dev/null
+++ b/ext/-test-/ensure_and_callcc/extconf.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: false
+require "mkmf"
+
+require_relative "../auto_ext.rb"
+auto_ext(inc: true)
diff --git a/test/-ext-/required.rb b/test/-ext-/required.rb
new file mode 100644
index 0000000000..70514355ff
--- /dev/null
+++ b/test/-ext-/required.rb
@@ -0,0 +1,10 @@
+require 'continuation'
+cont = nil
+a = [*1..10].reject do |i|
+  callcc {|c| cont = c} if !cont and i == 10
+  false
+end
+if a.size < 1000
+  a.unshift(:x)
+  cont.call
+end
diff --git a/test/-ext-/test_ensure_and_callcc.rb b/test/-ext-/test_ensure_and_callcc.rb
new file mode 100644
index 0000000000..90f8abbb3c
--- /dev/null
+++ b/test/-ext-/test_ensure_and_callcc.rb
@@ -0,0 +1,36 @@
+# -*- coding: us-ascii -*-
+# frozen_string_literal: false
+require 'test/unit'
+
+class TestEnsureAndCallcc < Test::Unit::TestCase
+  require '-test-/ensure_and_callcc'
+
+  def test_bug20655_dir_chdir_using_rb_ensure
+    need_continuation
+    called = 0
+    tmp = nil
+    Dir.chdir('/tmp') do
+      tmp = Dir.pwd
+      cont = nil
+      callcc{|c| cont = c}
+      assert_equal(tmp, Dir.pwd, "BUG #20655: ensure called and pwd was changed unexpectedly")
+      called += 1
+      cont.call if called < 10
+    end
+  end
+
+  def test_bug20655_extension_using_rb_ensure
+    need_continuation
+    $ensure_called = 0
+    require_with_ensure(File.join(__dir__, 'required'))
+    assert_equal(1, $ensure_called, "BUG #20655: ensure called unexpectedly in the required script even without exceptions")
+  end
+
+  private
+  def need_continuation
+    unless respond_to?(:callcc, true)
+      EnvUtil.suppress_warning {require 'continuation'}
+    end
+    omit 'requires callcc support' unless respond_to?(:callcc, true)
+  end
+end