diff --git a/ext/json/generator/generator.c b/ext/json/generator/generator.c
index efb6b4a0a2..a71acfbb76 100644
--- a/ext/json/generator/generator.c
+++ b/ext/json/generator/generator.c
@@ -16,7 +16,7 @@ static ID i_to_s, i_to_json, i_new, i_indent, i_space, i_space_before,
           i_object_nl, i_array_nl, i_max_nesting, i_allow_nan, i_ascii_only,
           i_pack, i_unpack, i_create_id, i_extend, i_key_p,
           i_aref, i_send, i_respond_to_p, i_match, i_keys, i_depth,
-          i_buffer_initial_length, i_dup, i_script_safe, i_escape_slash;
+          i_buffer_initial_length, i_dup, i_script_safe, i_escape_slash, i_strict;
 
 /*
  * Copyright 2001-2004 Unicode, Inc.
@@ -749,6 +749,8 @@ static VALUE cState_configure(VALUE self, VALUE opts)
         tmp = rb_hash_aref(opts, ID2SYM(i_escape_slash));
         state->script_safe = RTEST(tmp);
     }
+    tmp = rb_hash_aref(opts, ID2SYM(i_strict));
+    state->strict = RTEST(tmp);
     return self;
 }
 
@@ -784,6 +786,7 @@ static VALUE cState_to_h(VALUE self)
     rb_hash_aset(result, ID2SYM(i_ascii_only), state->ascii_only ? Qtrue : Qfalse);
     rb_hash_aset(result, ID2SYM(i_max_nesting), LONG2FIX(state->max_nesting));
     rb_hash_aset(result, ID2SYM(i_script_safe), state->script_safe ? Qtrue : Qfalse);
+    rb_hash_aset(result, ID2SYM(i_strict), state->strict ? Qtrue : Qfalse);
     rb_hash_aset(result, ID2SYM(i_depth), LONG2FIX(state->depth));
     rb_hash_aset(result, ID2SYM(i_buffer_initial_length), LONG2FIX(state->buffer_initial_length));
     return result;
@@ -1049,6 +1052,8 @@ static void generate_json(FBuffer *buffer, VALUE Vstate, JSON_Generator_State *s
         generate_json_bignum(buffer, Vstate, state, obj);
     } else if (klass == rb_cFloat) {
         generate_json_float(buffer, Vstate, state, obj);
+    } else if (state->strict) {
+        rb_raise(eGeneratorError, "%"PRIsVALUE" not allowed in JSON", RB_OBJ_STRING(CLASS_OF(obj)));
     } else if (rb_respond_to(obj, i_to_json)) {
         tmp = rb_funcall(obj, i_to_json, 1, Vstate);
         Check_Type(tmp, T_STRING);
@@ -1423,7 +1428,7 @@ static VALUE cState_script_safe(VALUE self)
 }
 
 /*
- * call-seq: script_safe=(depth)
+ * call-seq: script_safe=(enable)
  *
  * This sets whether or not the forward slashes will be escaped in
  * the json output.
@@ -1435,6 +1440,37 @@ static VALUE cState_script_safe_set(VALUE self, VALUE enable)
     return Qnil;
 }
 
+/*
+ * call-seq: strict
+ *
+ * If this boolean is false, types unsupported by the JSON format will
+ * be serialized as strings.
+ * If this boolean is true, types unsupported by the JSON format will
+ * raise a JSON::GeneratorError.
+ */
+static VALUE cState_strict(VALUE self)
+{
+    GET_STATE(self);
+    return state->strict ? Qtrue : Qfalse;
+}
+
+/*
+ * call-seq: strict=(enable)
+ *
+ * This sets whether or not to serialize types unsupported by the
+ * JSON format as strings.
+ * If this boolean is false, types unsupported by the JSON format will
+ * be serialized as strings.
+ * If this boolean is true, types unsupported by the JSON format will
+ * raise a JSON::GeneratorError.
+ */
+static VALUE cState_strict_set(VALUE self, VALUE enable)
+{
+    GET_STATE(self);
+    state->strict = RTEST(enable);
+    return Qnil;
+}
+
 /*
  * call-seq: allow_nan?
  *
@@ -1557,6 +1593,9 @@ void Init_generator(void)
     rb_define_alias(cState, "escape_slash", "script_safe");
     rb_define_alias(cState, "escape_slash?", "script_safe?");
     rb_define_alias(cState, "escape_slash=", "script_safe=");
+    rb_define_method(cState, "strict", cState_strict, 0);
+    rb_define_method(cState, "strict?", cState_strict, 0);
+    rb_define_method(cState, "strict=", cState_strict_set, 1);
     rb_define_method(cState, "check_circular?", cState_check_circular_p, 0);
     rb_define_method(cState, "allow_nan?", cState_allow_nan_p, 0);
     rb_define_method(cState, "ascii_only?", cState_ascii_only_p, 0);
@@ -1615,6 +1654,7 @@ void Init_generator(void)
     i_max_nesting = rb_intern("max_nesting");
     i_script_safe = rb_intern("script_safe");
     i_escape_slash = rb_intern("escape_slash");
+    i_strict = rb_intern("strict");
     i_allow_nan = rb_intern("allow_nan");
     i_ascii_only = rb_intern("ascii_only");
     i_depth = rb_intern("depth");
diff --git a/ext/json/generator/generator.h b/ext/json/generator/generator.h
index 5e6a228040..1a736b84dd 100644
--- a/ext/json/generator/generator.h
+++ b/ext/json/generator/generator.h
@@ -73,6 +73,7 @@ typedef struct JSON_Generator_StateStruct {
     char allow_nan;
     char ascii_only;
     char script_safe;
+    char strict;
     long depth;
     long buffer_initial_length;
 } JSON_Generator_State;
@@ -153,6 +154,8 @@ static VALUE cState_depth(VALUE self);
 static VALUE cState_depth_set(VALUE self, VALUE depth);
 static VALUE cState_script_safe(VALUE self);
 static VALUE cState_script_safe_set(VALUE self, VALUE depth);
+static VALUE cState_strict(VALUE self);
+static VALUE cState_strict_set(VALUE self, VALUE strict);
 static FBuffer *cState_prepare_buffer(VALUE self);
 #ifndef ZALLOC
 #define ZALLOC(type) ((type *)ruby_zalloc(sizeof(type)))
diff --git a/ext/json/lib/json/common.rb b/ext/json/lib/json/common.rb
index 68ff0efcd0..53b66a9bf6 100644
--- a/ext/json/lib/json/common.rb
+++ b/ext/json/lib/json/common.rb
@@ -3,6 +3,9 @@ require 'json/version'
 require 'json/generic_object'
 
 module JSON
+  NOT_SET = Object.new.freeze
+  private_constant :NOT_SET
+
   class << self
     # :call-seq:
     #   JSON[object] -> new_array or new_string
@@ -608,7 +611,7 @@ module JSON
   #   puts File.read(path)
   # Output:
   #   {"foo":[0,1],"bar":{"baz":2,"bat":3},"bam":"bad"}
-  def dump(obj, anIO = nil, limit = nil)
+  def dump(obj, anIO = nil, limit = nil, strict: NOT_SET)
     if anIO and limit.nil?
       anIO = anIO.to_io if anIO.respond_to?(:to_io)
       unless anIO.respond_to?(:write)
@@ -618,6 +621,7 @@ module JSON
     end
     opts = JSON.dump_default_options
     opts = opts.merge(:max_nesting => limit) if limit
+    opts[:strict] = strict if NOT_SET != strict
     result = generate(obj, opts)
     if anIO
       anIO.write result
diff --git a/ext/json/parser/parser.c b/ext/json/parser/parser.c
index bcd0816f90..57f87432b6 100644
--- a/ext/json/parser/parser.c
+++ b/ext/json/parser/parser.c
@@ -1902,7 +1902,7 @@ static VALUE cParser_initialize(int argc, VALUE *argv, VALUE self)
         json->max_nesting = 100;
         json->allow_nan = 0;
         json->create_additions = 0;
-        json->create_id = rb_funcall(mJSON, i_create_id, 0);
+        json->create_id = Qnil;
         json->object_class = Qnil;
         json->array_class = Qnil;
         json->decimal_class = Qnil;
diff --git a/ext/json/parser/parser.rl b/ext/json/parser/parser.rl
index e6d5d3c152..af190e7500 100644
--- a/ext/json/parser/parser.rl
+++ b/ext/json/parser/parser.rl
@@ -797,7 +797,7 @@ static VALUE cParser_initialize(int argc, VALUE *argv, VALUE self)
         json->max_nesting = 100;
         json->allow_nan = 0;
         json->create_additions = 0;
-        json->create_id = rb_funcall(mJSON, i_create_id, 0);
+        json->create_id = Qnil;
         json->object_class = Qnil;
         json->array_class = Qnil;
         json->decimal_class = Qnil;
diff --git a/test/json/json_generator_test.rb b/test/json/json_generator_test.rb
index 1bf4912ec7..46cbf9c7f7 100755
--- a/test/json/json_generator_test.rb
+++ b/test/json/json_generator_test.rb
@@ -150,6 +150,7 @@ EOT
       :buffer_initial_length => 1024,
       :depth                 => 0,
       :script_safe           => false,
+      :strict                => false,
       :indent                => "  ",
       :max_nesting           => 100,
       :object_nl             => "\n",
@@ -167,6 +168,7 @@ EOT
       :buffer_initial_length => 1024,
       :depth                 => 0,
       :script_safe           => false,
+      :strict                => false,
       :indent                => "",
       :max_nesting           => 100,
       :object_nl             => "",
@@ -184,6 +186,7 @@ EOT
       :buffer_initial_length => 1024,
       :depth                 => 0,
       :script_safe           => false,
+      :strict                => false,
       :indent                => "",
       :max_nesting           => 0,
       :object_nl             => "",
@@ -336,7 +339,13 @@ EOT
 
   def test_json_generate
     assert_raise JSON::GeneratorError do
-      assert_equal true, generate(["\xea"])
+      generate(["\xea"])
+    end
+  end
+
+  def test_json_generate_unsupported_types
+    assert_raise JSON::GeneratorError do
+      generate(Object.new, strict: true)
     end
   end