diff --git a/hash.c b/hash.c
index 0072852..e8bce24 100644
--- a/hash.c
+++ b/hash.c
@@ -2367,22 +2367,36 @@ flatten_i(VALUE key, VALUE val, VALUE ary)
  *     a =  {1=> "one", 2 => [2,"two"], 3 => "three"}
  *     a.flatten    # => [1, "one", 2, [2, "two"], 3, "three"]
  *     a.flatten(2) # => [1, "one", 2, 2, "two", 3, "three"]
+ *     a.flatten(0) # => [[1, "one"], [2, [2, "two"]], [3, "three"]]
+ *     a.flatten(-1) # => [1, "one", 2, 2, "two", 3, "three"]
  */
 
 static VALUE
 rb_hash_flatten(int argc, VALUE *argv, VALUE hash)
 {
     VALUE ary;
+    int level;
 
     ary = rb_ary_new_capa(RHASH_SIZE(hash) * 2);
     rb_hash_foreach(hash, flatten_i, ary);
-    if (argc) {
-	int level = NUM2INT(*argv) - 1;
-	if (level > 0) {
-	    *argv = INT2FIX(level);
-	    rb_funcall2(ary, rb_intern("flatten!"), argc, argv);
-	}
-    }
+    if (!argc) {
+      return ary;
+    }
+    
+    level = NUM2INT(*argv);
+    if (!level) {
+      ary = rb_hash_to_a(hash);
+    } else {
+      if (level > 0) {
+	level--;
+      }
+      if (!level) {
+	return ary;
+      }
+      *argv = INT2FIX(level);
+      rb_funcall2(ary, rb_intern("flatten!"), argc, argv);
+    }
+    
     return ary;
 }
 
diff --git a/test/ruby/test_hash.rb b/test/ruby/test_hash.rb
index c39cd23..b4e0847 100644
--- a/test/ruby/test_hash.rb
+++ b/test/ruby/test_hash.rb
@@ -974,8 +974,8 @@ class TestHash < Test::Unit::TestCase
 
     a =  @cls[1=> "one", 2 => [2,"two"], 3 => [3, ["three"]]]
     assert_equal([1, "one", 2, [2, "two"], 3, [3, ["three"]]], a.flatten)
-    assert_equal([1, "one", 2, [2, "two"], 3, [3, ["three"]]], a.flatten(-1))
-    assert_equal([1, "one", 2, [2, "two"], 3, [3, ["three"]]], a.flatten(0))
+    assert_equal([1, "one", 2, 2, "two", 3, 3, "three"], a.flatten(-1))
+    assert_equal([[1, "one"], [2, [2, "two"]], [3, [3, ["three"]]]], a.flatten(0))
     assert_equal([1, "one", 2, [2, "two"], 3, [3, ["three"]]], a.flatten(1))
     assert_equal([1, "one", 2, 2, "two", 3, 3, ["three"]], a.flatten(2))
     assert_equal([1, "one", 2, 2, "two", 3, 3, "three"], a.flatten(3))