diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1bbeafaa6..e79057ba9 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ ruby-head, '3.0', '2.7', '2.6' ]
+        ruby: [ '3.2', '3.3', '3.4' ]
     env:
       W_ERROR: '1'
     steps:
diff --git a/.gitignore b/.gitignore
index ebe20fa85..dd7e55ada 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,3 +15,5 @@
 mkmf.log
 /ext/mruby_engine/mruby-mpdecimal/tests/runtest
 /ext/mruby_engine/mruby-mpdecimal/tests/runtest_alloc
+
+mruby_config.rb.lock
diff --git a/.gitmodules b/.gitmodules
index b332c546e..f053377b3 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,4 +1,4 @@
 [submodule "ext/mruby_engine/mruby"]
 	path = ext/mruby_engine/mruby
 	url = https://github.com/Shopify/mruby.git
-	branch = mruby-engine-submodule
+	branch = jringer/better-distinguish-clang
diff --git a/ext/mruby_engine/dlmalloc_config.h b/ext/mruby_engine/dlmalloc_config.h
index 1671068e4..0682267b8 100644
--- a/ext/mruby_engine/dlmalloc_config.h
+++ b/ext/mruby_engine/dlmalloc_config.h
@@ -2,7 +2,7 @@
 #define MRUBY_ENGINE_DLMALLOC_CONFIG_H
 
 #define ONLY_MSPACES 1
-#define HAVE_MREMAP 0
+
 //#define FOOTERS 1
 
 #include "host.h"
diff --git a/ext/mruby_engine/host.c b/ext/mruby_engine/host.c
index 055e742a9..5878daceb 100644
--- a/ext/mruby_engine/host.c
+++ b/ext/mruby_engine/host.c
@@ -4,6 +4,7 @@
 #include <libunwind.h>
 #include <ruby.h>
 #include <ruby/thread.h>
+#include <stdio.h>
 #include <string.h>
 
 const intptr_t ME_HOST_NIL = Qnil;
diff --git a/ext/mruby_engine/mruby b/ext/mruby_engine/mruby
index 8f6b22b53..ad8eb41e6 160000
--- a/ext/mruby_engine/mruby
+++ b/ext/mruby_engine/mruby
@@ -1 +1 @@
-Subproject commit 8f6b22b53d0a11f4f1146cbc6de372ed8126e1b8
+Subproject commit ad8eb41e668043b5c8ef56bbd864460714acad70
diff --git a/ext/mruby_engine/mruby-mpdecimal/tests/Makefile b/ext/mruby_engine/mruby-mpdecimal/tests/Makefile
index 6591a67da..f9bd07918 100644
--- a/ext/mruby_engine/mruby-mpdecimal/tests/Makefile
+++ b/ext/mruby_engine/mruby-mpdecimal/tests/Makefile
@@ -5,9 +5,9 @@ LD = gcc
 AR = ar
 
 MPD_WARN = -Wall -W -Wno-unknown-pragmas -std=c99 -pedantic
-MPD_CONFIG = -DCONFIG_64 -DASM
+MPD_CONFIG = -DCONFIG_64 -DANSI -DHAVE_UINT128_T
 
-CONFIGURE_CFLAGS = -ggdb -Wall -W -Wno-unknown-pragmas -std=c99 -pedantic -DCONFIG_64 -DASM -O0
+CONFIGURE_CFLAGS = -ggdb -Wall -W -Wno-unknown-pragmas -std=c99 -pedantic -DCONFIG_64 -DANSI -DHAVE_UINT128_T -O0
 CFLAGS ?= $(CONFIGURE_CFLAGS)
 
 HEADERS = $(wildcard $(SRCDIR)/*.h)
diff --git a/ext/mruby_engine/mruby_engine.c b/ext/mruby_engine/mruby_engine.c
index 60d448029..020e0fe5c 100644
--- a/ext/mruby_engine/mruby_engine.c
+++ b/ext/mruby_engine/mruby_engine.c
@@ -102,7 +102,7 @@ me_host_exception_t me_mruby_engine_get_exception(struct me_mruby_engine *self)
 
   intptr_t host_backtrace = me_host_backtrace_new();
   mrb_value backtrace = mrb_exc_backtrace(self->state, exception);
-  mrb_int backtrace_len = mrb_ary_len(self->state, backtrace);
+  mrb_int backtrace_len = RARRAY_LEN(backtrace);
   for (int i = 0; i < backtrace_len; ++i) {
     mrb_value location = mrb_ary_entry(backtrace, i);
     me_host_backtrace_push_location(host_backtrace, mrb_string_value_cstr(self->state, &location));
@@ -139,7 +139,7 @@ static void mruby_engine_check_stack(
 static void mruby_engine_code_fetch_hook(
   struct mrb_state* mrb,
   struct mrb_irep *irep,
-  mrb_code *pc,
+  const mrb_code *pc,
   mrb_value *regs)
 {
   (void)irep;
@@ -244,7 +244,7 @@ static struct RProc *generate_code(
 
   if (parser_state->nerr > 0) {
     *err = me_host_syntax_error_new(
-      parser_state->filename,
+      mrb_sym_name(state, parser_state->filename_sym),
       parser_state->error_buffer[0].lineno,
       parser_state->error_buffer[0].column,
       parser_state->error_buffer[0].message);
@@ -393,7 +393,7 @@ struct me_iseq *me_iseq_new(
   int status = mrb_dump_irep(
     engine->state,
     irep,
-    DUMP_DEBUG_INFO | DUMP_ENDIAN_NAT,
+    DUMP_DEBUG_INFO,
     &irep_data,
     &irep_data_size);
   if (status == MRB_DUMP_OK) {
diff --git a/ext/mruby_engine/value_guest.c b/ext/mruby_engine/value_guest.c
index 2b0e3279a..42f7b562e 100644
--- a/ext/mruby_engine/value_guest.c
+++ b/ext/mruby_engine/value_guest.c
@@ -48,7 +48,7 @@ static me_host_value_t me_value_to_host_r(
         return ME_HOST_NIL;
       }
 
-      for (mrb_int i = 0, f = mrb_ary_len(self->state, value); i < f; ++i) {
+      for (mrb_int i = 0, f = RARRAY_LEN(value); i < f; ++i) {
         me_host_value_t element = me_value_to_host_r(
           self, mrb_ary_ref(self->state, value, i), depth + 1, err);
         if (err->type != ME_VALUE_NO_ERR) {
@@ -69,20 +69,19 @@ static me_host_value_t me_value_to_host_r(
         return ME_HOST_NIL;
       }
 
-      struct kh_ht *kh = mrb_hash_tbl(self->state, value);
-      for (int i = kh_begin(kh), f = kh_end(kh); i < f; ++i) {
-        if (!kh_exist(kh, i)) {
-          continue;
-        }
+      mrb_value keys = mrb_hash_keys(self->state, value);
+      mrb_int len = RARRAY_LEN(keys);
+      for (mrb_int i = 0; i < len; ++i) {
+        mrb_value k = mrb_ary_ref(self->state, keys, i);
 
         me_host_value_t key = me_value_to_host_r(
-          self, kh_key(kh, i), depth + 1, err);
+          self, k, depth + 1, err);
         if (err->type != ME_VALUE_NO_ERR) {
           return ME_HOST_NIL;
         }
 
         me_host_value_t element = me_value_to_host_r(
-          self, kh_value(kh, i).v, depth + 1, err);
+          self, mrb_hash_get(self->state, value, k), depth + 1, err);
         if (err->type != ME_VALUE_NO_ERR) {
           return ME_HOST_NIL;
         }
diff --git a/mruby_engine.gemspec b/mruby_engine.gemspec
index c1e651b4c..1e3ef8f6e 100644
--- a/mruby_engine.gemspec
+++ b/mruby_engine.gemspec
@@ -47,9 +47,10 @@ Gem::Specification.new do |spec|
 
   spec.add_runtime_dependency "getoptlong"
 
+  spec.add_development_dependency "bigdecimal"
   spec.add_development_dependency "bundler", ">= 1.6"
-  spec.add_development_dependency "rake", "~> 10.4"
-  spec.add_development_dependency "rake-compiler", "~> 0.9"
+  spec.add_development_dependency "rake", ">= 12.0"
+  spec.add_development_dependency "rake-compiler", ">= 1.2"
   spec.add_development_dependency "rspec", "~> 3.3"
   spec.add_development_dependency "pry", "~> 0.10.0"
   spec.add_development_dependency "pry-byebug", "~> 3.1"
diff --git a/spec/arbitrary.rb b/spec/arbitrary.rb
index 423b7663d..1b3b3dab1 100644
--- a/spec/arbitrary.rb
+++ b/spec/arbitrary.rb
@@ -3,7 +3,7 @@
 require "securerandom"
 
 module Arbitrary
-  refine Fixnum.singleton_class do
+  refine Integer.singleton_class do
     def arbitrary
       lambda do
         if SecureRandom.random_number(2) == 0
@@ -21,7 +21,7 @@ def arbitrary_natural
     end
   end
 
-  refine Fixnum do
+  refine Integer do
     def shrink
       if self > 2 || -2 < self
         [(self / 2).to_i]
@@ -34,7 +34,7 @@ def shrink
   refine BigDecimal.singleton_class do
     def arbitrary
       lambda do
-        "#{Fixnum.arbitrary.call}.#{Fixnum.arbitrary_natural.call}".to_d
+        "#{Integer.arbitrary.call}.#{Integer.arbitrary_natural.call}".to_d
       end
     end
   end
diff --git a/spec/mruby_engine_spec.rb b/spec/mruby_engine_spec.rb
index 2ef18a5f1..ce77da877 100644
--- a/spec/mruby_engine_spec.rb
+++ b/spec/mruby_engine_spec.rb
@@ -144,8 +144,8 @@ def bar
       SOURCE
     }.to raise_error(MRubyEngine::EngineRuntimeError) do |e|
       expect(e.guest_backtrace).to eq([
-        "backtrace.rb:2:in Object.foo",
-        "backtrace.rb:6:in Object.bar",
+        "backtrace.rb:2:in foo",
+        "backtrace.rb:6:in bar",
         "backtrace.rb:9",
       ])
     end
@@ -183,7 +183,7 @@ def self.to_s
         raise(TransmogrificationError, "This looks bad.")
       SOURCE
     }.to raise_error(MRubyEngine::EngineRuntimeError) do |e|
-      expect(e.type).to match(/\A#<Class:0x\h+>\z/)
+      expect(e.type).to match(/\ATransmogrificationError\z|\A#<Class:0x\h+>\z/)
     end
   end
 
@@ -508,7 +508,7 @@ def initialize
       it "returns the compiled instructions" do
         iseq = MRubyEngine::InstructionSequence.new([["sample.rb", "@foo = 42"]])
         expect(iseq.data.encoding).to eq(Encoding::ASCII_8BIT)
-        expect(iseq.data.size).to eq(127)
+        expect(iseq.data.size).to eq(136)
       end
     end
 
diff --git a/spec/time_spec.rb b/spec/time_spec.rb
index 7fb47fe67..d56d40f5c 100644
--- a/spec/time_spec.rb
+++ b/spec/time_spec.rb
@@ -80,7 +80,7 @@ def eval_test(source)
 
   it "raises if time is out of range" do
     eval_test(<<-SOURCE)
-      assert_raises(ArgumentError, "9.3674872249306e+17 out of Time range") do
+      assert_raises(ArgumentError, "9.367487224930632e+17 out of Time range") do
         Time.at(0xd00000000000000)
       end
     SOURCE