diff --git a/Rakefile b/Rakefile
index 81d54a2..e02aa4a 100755
--- a/Rakefile
+++ b/Rakefile
@@ -9,7 +9,6 @@ require 'uri'
 require 'net/http'
 require 'open3'
 require 'etc'
-require 'fileutils'
 require 'pathname'
 require 'rake/clean'
 
@@ -57,10 +56,12 @@ class BuildTarget
       .split(' ').last.strip
   end
 
-  def configuration
+  def configuration(prefix)
     case @architecture
     when :rv32
-      ['--with-arch=rv32imafdc', '--with-abi=ilp32d', '--with-tune=rocket', '--with-isa-spec=20191213']
+      ['arch=rv32imafdc', 'abi=ilp32d', 'tune=rocket', 'isa-spec=20191213'].map do |option|
+        "-#{prefix}#{option}"
+      end
     else
       []
     end
@@ -109,9 +110,9 @@ end
 
 def configure_make_install(source_directory, configure_options, env, cwd)
   configure = source_directory.relative_path_from(cwd) + 'configure'
-  system env, configure.to_path, *configure_options, chdir: cwd.to_path, exception: true
-  system 'make', '-j', Etc.nprocessors.to_s, chdir: cwd.to_path, exception: true
-  system env, 'make', 'install', chdir: cwd.to_path, exception: true
+  sh env, configure.to_path, *configure_options, chdir: cwd.to_path
+  sh 'make', '-j', Etc.nprocessors.to_s, chdir: cwd.to_path
+  sh env, 'make', 'install', chdir: cwd.to_path
 end
 
 directory(TMP + 'tools')
@@ -168,8 +169,8 @@ namespace :cross do
     options.rootfs.mkpath
     options.sysroot.mkpath
 
-    system 'contrib/download_prerequisites', chdir: source_directory.to_path, exception: true
-    configure_options = options.configuration + [
+    sh 'contrib/download_prerequisites', chdir: source_directory.to_path
+    configure_options = options.configuration('-with-') + [
       "--prefix=#{options.rootfs.realpath}",
       "--with-sysroot=#{options.sysroot.realpath}",
       '--enable-languages=c,c++',
@@ -211,7 +212,7 @@ namespace :cross do
     include_directory = TMP + 'tools/include'
 
     include_directory.mkpath
-    FileUtils.cp (source_directory + 'elf/elf.h'), (include_directory + 'elf.h')
+    cp (source_directory + 'elf/elf.h'), (include_directory + 'elf.h')
   end
 
   desc 'Build linux kernel'
@@ -226,14 +227,14 @@ namespace :cross do
       'PATH' => "#{options.rootfs.realpath + 'bin'}:#{ENV['PATH']}",
       'HOSTCFLAGS' => "-D_UUID_T -D__GETHOSTUUID_H -I#{TMP + 'tools/include'}"
     }
-    system env, 'make', 'rv32_defconfig', chdir: cwd.to_path, exception: true
-    system env, 'make', '-j', Etc.nprocessors.to_s, chdir: cwd.to_path, exception: true
-    system env, 'make', 'headers', chdir: cwd.to_path, exception: true
+    sh env, 'make', 'rv32_defconfig', chdir: cwd.to_path
+    sh env, 'make', '-j', Etc.nprocessors.to_s, chdir: cwd.to_path
+    sh env, 'make', 'headers', chdir: cwd.to_path
 
     user_directory = options.sysroot + 'usr'
 
     user_directory.mkpath
-    FileUtils.cp_r (cwd + 'usr/include'), (user_directory + 'include')
+    cp_r (cwd + 'usr/include'), (user_directory + 'include')
   end
 
   desc 'Build glibc'
@@ -275,13 +276,14 @@ namespace :cross do
     source_directory = TMP + "tools/gcc-#{GCC_VERSION}"
     cwd = TMP + 'tools/build-gcc'
 
-    FileUtils.rm_rf cwd
+    rm_rf cwd
     cwd.mkpath
+    cp_r '../elna', source_directory + 'gcc'
 
-    configure_options = options.configuration + [
+    configure_options = options.configuration('-with-') + [
       "--prefix=#{options.rootfs.realpath}",
       "--with-sysroot=#{options.sysroot.realpath}",
-      '--enable-languages=c,c++,lto',
+      '--enable-languages=c,c++,lto,elna',
       '--enable-lto',
       '--enable-shared',
       '--disable-bootstrap',
@@ -308,7 +310,7 @@ end
 
 task cross: TMP + 'tools'
 task :cross, :target do |t, args|
-  args.with_defaults(target: 'riscv32-unknown-linux-gnu')
+  args.with_defaults target: 'riscv32'
 
   Rake::Task['cross:binutils'].invoke args[:target]
   Rake::Task['cross:gcc1'].invoke args[:target]
@@ -318,27 +320,55 @@ task :cross, :target do |t, args|
   Rake::Task['cross:gcc2'].invoke args[:target]
 end
 
-FLAGS = ['-O2', '-g3', '-Wall', '-march=rv32imzicsr', '-mabi=ilp32', '-fno-stack-protector', '-ffreestanding', '-nostdlib', '-static']
-
-CLEAN.include 'kernel.elf', 'build/riscv32'
+def relative_from_tmp(path)
+  Pathname.new(path).relative_path_from(TMP).each_filename
+end
 
+CLEAN.include(TMP + 'riscv32')
 directory(TMP + 'riscv32')
 
-rule(/^#{TMP}\/[[:alnum:]]+\/[[:alnum:]]+\.o$/ => ->(match) {
-  [Pathname.new(match).basename.sub_ext('.s'), TMP + 'riscv32']
-}) do |t|
-  ENV['CC'] = 'build/rootfs/bin/riscv32-unknown-linux-gnu-gcc'
+rule '.s.o' => ->(match) {
+  architecture, *path_components = relative_from_tmp(match).to_a
+  path_components[-1] = path_components.last.ext('')
 
-  system ENV['CC'], *FLAGS, '-c', '-o', t.name, *t.prerequisites.select { |prerequisite| prerequisite.end_with? '.s' }
+  [File.join(path_components), TMP + architecture]
+} do |t|
+  options = BuildTarget.new relative_from_tmp(t.name).first
+  compiler = options.rootfs + "bin/#{options.target}-gcc"
+  flags = ['-ffreestanding'] + options.configuration('m')
+  sources = t.prerequisites.select { |prerequisite| File.extname(prerequisite) == '.s' }
+
+  system compiler.to_s, *flags, '-c', '-o', t.name, *sources, exception: true
 end
 
-file 'kernel.elf' => FileList['*.s'].map { |source| (TMP + 'riscv32' + source).sub_ext('.o') } do |t|
-  ENV['CC'] = 'build/rootfs/bin/riscv32-unknown-linux-gnu-gcc'
+rule '.elna.o' => ->(match) {
+  architecture, *path_components = relative_from_tmp(match).to_a
+  path_components[-1] = path_components.last.ext('')
 
-  system ENV['CC'], *FLAGS, '-T', 'kernel.ld', '-Wl,-Map=kernel.map', '-o', 'kernel.elf', *t.prerequisites
+  [File.join(path_components), TMP + architecture]
+} do |t|
+  options = BuildTarget.new relative_from_tmp(t.name).first
+  compiler = options.rootfs + "bin/#{options.target}-gcc"
+  flags = ['-O2', '-g3', '-fno-stack-protector'] + options.configuration('m')
+  sources = t.prerequisites.select { |prerequisite| File.extname(prerequisite) == '.elna' }
+
+  system compiler.to_s, *flags, '-c', '-o', t.name, *sources, exception: true
 end
 
-task default: 'kernel.elf'
+rule 'kernel.elf' => ->(match) {
+  architecture_tmp = TMP + relative_from_tmp(match).first
+
+  FileList['*.s', '*.elna'].map { |source| (architecture_tmp + source).to_path + '.o' } << 'kernel.ld'
+} do |t|
+  options = BuildTarget.new relative_from_tmp(t.name).first
+  compiler = options.rootfs + "bin/#{options.target}-gcc"
+  flags = options.configuration('m')
+  objects, linker_script = t.prerequisites.partition { |prerequisite| File.extname(prerequisite) == '.o' }
+
+  system compiler.to_s, '-nostdlib', '-T', *linker_script, '-o', t.name, *objects, exception: true
+end
+
+task default: 'build/riscv32/kernel.elf'
 task :default do |t|
   QEMU = 'qemu-system-riscv32'
 
diff --git a/kernel.s b/kernel.s
index c069cd8..9ff500b 100644
--- a/kernel.s
+++ b/kernel.s
@@ -140,13 +140,13 @@ handle_trap:
 	csrr a0, scause
 	call write_i
 
-	li a0, ','
+	call separator
 	call write_c
 
 	csrr a0, stval
 	call write_i
 
-	li a0, ','
+	call separator
 	call write_c
 
 	csrr a0, sepc
diff --git a/source.elna b/source.elna
new file mode 100644
index 0000000..55052a4
--- /dev/null
+++ b/source.elna
@@ -0,0 +1,7 @@
+module;
+
+proc separator*() -> Char;
+  return ','
+end;
+
+end.