diff --git a/CHANGES b/CHANGES
index f0e6c6eb..bba29be6 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+2010-05-05 (1.4.3)
+  * Fixed some test assertions, from Ruby r27587 and r27590, patch by nobu.
+  * Fixed issue http://github.com/flori/json/issues/#issue/20 reported by
+    electronicwhisper@github. Thx!
 2010-04-26 (1.4.2)
   * Applied patch from naruse Yui NARUSE <naruse@airemix.com> to make building with
     Microsoft Visual C possible again.
diff --git a/VERSION b/VERSION
index 9df886c4..428b770e 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.4.2
+1.4.3
diff --git a/ext/json/ext/generator/generator.c b/ext/json/ext/generator/generator.c
index b398cac3..f9a7d060 100644
--- a/ext/json/ext/generator/generator.c
+++ b/ext/json/ext/generator/generator.c
@@ -738,150 +738,132 @@ static VALUE cState_aref(VALUE self, VALUE name)
 static void generate_json(FBuffer *buffer, VALUE Vstate, JSON_Generator_State *state, VALUE obj, long depth)
 {
     VALUE tmp;
-    switch (TYPE(obj)) {
-        case T_HASH:
-            {
-                char *object_nl = state->object_nl;
-                long object_nl_len = state->object_nl_len;
-                char *indent = state->indent;
-                long indent_len = state->indent_len;
-                long max_nesting = state->max_nesting;
-                char *delim = FBUFFER_PTR(state->object_delim);
-                long delim_len = FBUFFER_LEN(state->object_delim);
-                char *delim2 = FBUFFER_PTR(state->object_delim2);
-                long delim2_len = FBUFFER_LEN(state->object_delim2);
-                int i, j;
-                VALUE key, key_to_s, keys;
-                depth++;
-                if (max_nesting != 0 && depth > max_nesting) {
-                    fbuffer_free(buffer);
-                    rb_raise(eNestingError, "nesting of %ld is too deep", depth);
-                }
-                fbuffer_append_char(buffer, '{');
-                keys = rb_funcall(obj, rb_intern("keys"), 0);
-                for(i = 0; i < RARRAY_LEN(keys); i++) {
-                    if (i > 0) fbuffer_append(buffer, delim, delim_len);
-                    if (object_nl) {
-                        fbuffer_append(buffer, object_nl, object_nl_len);
-                    }
-                    if (indent) {
-                        for (j = 0; j < depth; j++) {
-                            fbuffer_append(buffer, indent, indent_len);
-                        }
-                    }
-                    key = rb_ary_entry(keys, i);
-                    key_to_s = rb_funcall(key, i_to_s, 0);
-                    Check_Type(key_to_s, T_STRING);
-                    generate_json(buffer, Vstate, state, key_to_s, depth);
-                    fbuffer_append(buffer, delim2, delim2_len);
-                    generate_json(buffer, Vstate, state, rb_hash_aref(obj, key), depth);
-                }
-                depth--;
-                if (object_nl) {
-                    fbuffer_append(buffer, object_nl, object_nl_len);
-                    if (indent) {
-                        for (j = 0; j < depth; j++) {
-                            fbuffer_append(buffer, indent, indent_len);
-                        }
-                    }
+    VALUE klass = CLASS_OF(obj);
+    if (klass == rb_cHash) {
+        char *object_nl = state->object_nl;
+        long object_nl_len = state->object_nl_len;
+        char *indent = state->indent;
+        long indent_len = state->indent_len;
+        long max_nesting = state->max_nesting;
+        char *delim = FBUFFER_PTR(state->object_delim);
+        long delim_len = FBUFFER_LEN(state->object_delim);
+        char *delim2 = FBUFFER_PTR(state->object_delim2);
+        long delim2_len = FBUFFER_LEN(state->object_delim2);
+        int i, j;
+        VALUE key, key_to_s, keys;
+        depth++;
+        if (max_nesting != 0 && depth > max_nesting) {
+            fbuffer_free(buffer);
+            rb_raise(eNestingError, "nesting of %ld is too deep", depth);
+        }
+        fbuffer_append_char(buffer, '{');
+        keys = rb_funcall(obj, rb_intern("keys"), 0);
+        for(i = 0; i < RARRAY_LEN(keys); i++) {
+            if (i > 0) fbuffer_append(buffer, delim, delim_len);
+            if (object_nl) {
+                fbuffer_append(buffer, object_nl, object_nl_len);
+            }
+            if (indent) {
+                for (j = 0; j < depth; j++) {
+                    fbuffer_append(buffer, indent, indent_len);
                 }
-                fbuffer_append_char(buffer, '}');
             }
-            break;
-        case T_ARRAY:
-            {
-                char *array_nl = state->array_nl;
-                long array_nl_len = state->array_nl_len;
-                char *indent = state->indent;
-                long indent_len = state->indent_len;
-                long max_nesting = state->max_nesting;
-                char *delim = FBUFFER_PTR(state->array_delim);
-                long delim_len = FBUFFER_LEN(state->array_delim);
-                int i, j;
-                depth++;
-                if (max_nesting != 0 && depth > max_nesting) {
-                    fbuffer_free(buffer);
-                    rb_raise(eNestingError, "nesting of %ld is too deep", depth);
+            key = rb_ary_entry(keys, i);
+            key_to_s = rb_funcall(key, i_to_s, 0);
+            Check_Type(key_to_s, T_STRING);
+            generate_json(buffer, Vstate, state, key_to_s, depth);
+            fbuffer_append(buffer, delim2, delim2_len);
+            generate_json(buffer, Vstate, state, rb_hash_aref(obj, key), depth);
+        }
+        depth--;
+        if (object_nl) {
+            fbuffer_append(buffer, object_nl, object_nl_len);
+            if (indent) {
+                for (j = 0; j < depth; j++) {
+                    fbuffer_append(buffer, indent, indent_len);
                 }
-                fbuffer_append_char(buffer, '[');
-                if (array_nl) fbuffer_append(buffer, array_nl, array_nl_len);
-                for(i = 0; i < RARRAY_LEN(obj); i++) {
-                    if (i > 0) fbuffer_append(buffer, delim, delim_len);
-                    if (indent) {
-                        for (j = 0; j < depth; j++) {
-                            fbuffer_append(buffer, indent, indent_len);
-                        }
-                    }
-                    generate_json(buffer, Vstate, state, rb_ary_entry(obj, i), depth);
+            }
+        }
+        fbuffer_append_char(buffer, '}');
+    } else if (klass == rb_cArray) {
+        char *array_nl = state->array_nl;
+        long array_nl_len = state->array_nl_len;
+        char *indent = state->indent;
+        long indent_len = state->indent_len;
+        long max_nesting = state->max_nesting;
+        char *delim = FBUFFER_PTR(state->array_delim);
+        long delim_len = FBUFFER_LEN(state->array_delim);
+        int i, j;
+        depth++;
+        if (max_nesting != 0 && depth > max_nesting) {
+            fbuffer_free(buffer);
+            rb_raise(eNestingError, "nesting of %ld is too deep", depth);
+        }
+        fbuffer_append_char(buffer, '[');
+        if (array_nl) fbuffer_append(buffer, array_nl, array_nl_len);
+        for(i = 0; i < RARRAY_LEN(obj); i++) {
+            if (i > 0) fbuffer_append(buffer, delim, delim_len);
+            if (indent) {
+                for (j = 0; j < depth; j++) {
+                    fbuffer_append(buffer, indent, indent_len);
                 }
-                depth--;
-                if (array_nl) {
-                    fbuffer_append(buffer, array_nl, array_nl_len);
-                    if (indent) {
-                        for (j = 0; j < depth; j++) {
-                            fbuffer_append(buffer, indent, indent_len);
-                        }
-                    }
+            }
+            generate_json(buffer, Vstate, state, rb_ary_entry(obj, i), depth);
+        }
+        depth--;
+        if (array_nl) {
+            fbuffer_append(buffer, array_nl, array_nl_len);
+            if (indent) {
+                for (j = 0; j < depth; j++) {
+                    fbuffer_append(buffer, indent, indent_len);
                 }
-                fbuffer_append_char(buffer, ']');
             }
-            break;
-        case T_STRING:
-            fbuffer_append_char(buffer, '"');
+        }
+        fbuffer_append_char(buffer, ']');
+    } else if (klass == rb_cString) {
+        fbuffer_append_char(buffer, '"');
 #ifdef HAVE_RUBY_ENCODING_H
-            obj = rb_funcall(obj, i_encode, 1, CEncoding_UTF_8);
+        obj = rb_funcall(obj, i_encode, 1, CEncoding_UTF_8);
 #endif
-            if (state->ascii_only) {
-                convert_UTF8_to_JSON_ASCII(buffer, obj);
-            } else {
-                convert_UTF8_to_JSON(buffer, obj);
-            }
-            fbuffer_append_char(buffer, '"');
-            break;
-        case T_NIL:
-            fbuffer_append(buffer, "null", 4);
-            break;
-        case T_FALSE:
-            fbuffer_append(buffer, "false", 5);
-            break;
-        case T_TRUE:
-            fbuffer_append(buffer, "true", 4);
-            break;
-        case T_FIXNUM:
-            fbuffer_append_long(buffer, FIX2LONG(obj));
-            break;
-        case T_BIGNUM:
-            tmp = rb_funcall(obj, i_to_s, 0);
-            fbuffer_append(buffer, RSTRING_PAIR(tmp));
-            break;
-        case T_FLOAT:
-            {
-                double value = RFLOAT_VALUE(obj);
-                char allow_nan = state->allow_nan;
-                tmp = rb_funcall(obj, i_to_s, 0);
-                if (!allow_nan) {
-                    if (isinf(value)) {
-                        fbuffer_free(buffer);
-                        rb_raise(eGeneratorError, "%u: %s not allowed in JSON", __LINE__, StringValueCStr(tmp));
-                    } else if (isnan(value)) {
-                        fbuffer_free(buffer);
-                        rb_raise(eGeneratorError, "%u: %s not allowed in JSON", __LINE__, StringValueCStr(tmp));
-                    }
-                }
-                fbuffer_append(buffer, RSTRING_PAIR(tmp));
-            }
-            break;
-        default:
-            if (rb_respond_to(obj, i_to_json)) {
-                tmp = rb_funcall(obj, i_to_json, 2, Vstate, INT2FIX(depth + 1));
-                Check_Type(tmp, T_STRING);
-                fbuffer_append(buffer, RSTRING_PAIR(tmp));
-            } else {
-                tmp = rb_funcall(obj, i_to_s, 0);
-                Check_Type(tmp, T_STRING);
-                generate_json(buffer, Vstate, state, tmp, depth + 1);
+        if (state->ascii_only) {
+            convert_UTF8_to_JSON_ASCII(buffer, obj);
+        } else {
+            convert_UTF8_to_JSON(buffer, obj);
+        }
+        fbuffer_append_char(buffer, '"');
+    } else if (obj == Qnil) {
+        fbuffer_append(buffer, "null", 4);
+    } else if (obj == Qfalse) {
+        fbuffer_append(buffer, "false", 5);
+    } else if (obj == Qtrue) {
+        fbuffer_append(buffer, "true", 4);
+    } else if (klass == rb_cFixnum) {
+        fbuffer_append_long(buffer, FIX2LONG(obj));
+    } else if (klass == rb_cBignum) {
+        tmp = rb_funcall(obj, i_to_s, 0);
+        fbuffer_append(buffer, RSTRING_PAIR(tmp));
+    } else if (klass == rb_cFloat) {
+        double value = RFLOAT_VALUE(obj);
+        char allow_nan = state->allow_nan;
+        tmp = rb_funcall(obj, i_to_s, 0);
+        if (!allow_nan) {
+            if (isinf(value)) {
+                fbuffer_free(buffer);
+                rb_raise(eGeneratorError, "%u: %s not allowed in JSON", __LINE__, StringValueCStr(tmp));
+            } else if (isnan(value)) {
+                fbuffer_free(buffer);
+                rb_raise(eGeneratorError, "%u: %s not allowed in JSON", __LINE__, StringValueCStr(tmp));
             }
-            break;
+        }
+        fbuffer_append(buffer, RSTRING_PAIR(tmp));
+    } else if (rb_respond_to(obj, i_to_json)) {
+        tmp = rb_funcall(obj, i_to_json, 2, Vstate, INT2FIX(depth + 1));
+        Check_Type(tmp, T_STRING);
+        fbuffer_append(buffer, RSTRING_PAIR(tmp));
+    } else {
+        tmp = rb_funcall(obj, i_to_s, 0);
+        Check_Type(tmp, T_STRING);
+        generate_json(buffer, Vstate, state, tmp, depth + 1);
     }
 }
 
diff --git a/lib/json/version.rb b/lib/json/version.rb
index de7690b5..a06d1578 100644
--- a/lib/json/version.rb
+++ b/lib/json/version.rb
@@ -1,6 +1,6 @@
 module JSON
   # JSON version
-  VERSION         = '1.4.2'
+  VERSION         = '1.4.3'
   VERSION_ARRAY   = VERSION.split(/\./).map { |x| x.to_i } # :nodoc:
   VERSION_MAJOR   = VERSION_ARRAY[0] # :nodoc:
   VERSION_MINOR   = VERSION_ARRAY[1] # :nodoc:
diff --git a/tests/test_json.rb b/tests/test_json.rb
index f5a432f8..19b742f0 100755
--- a/tests/test_json.rb
+++ b/tests/test_json.rb
@@ -173,7 +173,18 @@ def test_parse_object
     assert_equal({'foo'=>'bar'}, parse('    { "foo"  :   "bar"   }   '))
   end
 
-  class SubHash < Hash; end
+  class SubHash < Hash
+    def to_json(*a)
+      {
+        JSON.create_id => self.class.name,
+      }.merge(self).to_json(*a)
+    end
+
+    def self.json_create(o)
+      o.delete JSON.create_id
+      new.merge(o)
+    end
+  end
 
   def test_parse_object_custom_class
     res = parse('{}', :object_class => SubHash)
@@ -181,6 +192,16 @@ def test_parse_object_custom_class
     assert_equal(SubHash, res.class)
   end
 
+  def test_generation_of_core_subclasses
+    obj = SubHash.new.merge( "foo" => SubHash.new.merge("bar" => true))
+    obj_json = JSON(obj)
+    obj_again = JSON(obj_json)
+    assert_kind_of SubHash, obj_again
+    assert_kind_of SubHash, obj_again['foo']
+    assert obj_again['foo']['bar']
+    assert_equal obj, obj_again
+  end
+
   def test_parser_reset
     parser = Parser.new(@json)
     assert_equal(@hash, parser.parse)