diff --git a/io.c b/io.c
index 99513573d7..2fe092b84e 100644
--- a/io.c
+++ b/io.c
@@ -8407,6 +8407,7 @@ rb_io_init_copy(VALUE dest, VALUE io)
     fptr->encs = orig->encs;
     fptr->pid = orig->pid;
     fptr->lineno = orig->lineno;
+    fptr->timeout = orig->timeout;
     if (!NIL_P(orig->pathv)) fptr->pathv = orig->pathv;
     fptr_copy_finalizer(fptr, orig);
 
diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index 0c8beb2f95..989c4c8991 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -1441,6 +1441,14 @@ class TestIO < Test::Unit::TestCase
     End
   end
 
+  def test_dup_timeout
+    with_pipe do |r, w|
+      r.timeout = 0.1
+      r2 = r.dup
+      assert_equal(0.1, r2.timeout)
+    end
+  end
+
   def test_inspect
     with_pipe do |r, w|
       assert_match(/^#<IO:fd \d+>$/, r.inspect)