diff --git a/lib/vaporware/compiler.rb b/lib/vaporware/compiler.rb
index bd48cfc..1a696dd 100644
--- a/lib/vaporware/compiler.rb
+++ b/lib/vaporware/compiler.rb
@@ -40,7 +40,7 @@ def compile(compiler: "gcc", compiler_options: ["-O0"])
       end
       output.close
       compiler_options += @generator.compile_shared_option if @generator.shared
-      @generator.call_compiler(compiler:, compiler_options:)
+      @generator.to_elf(input: @generator.precompile, compiler:, compiler_options:, debug: @generator.debug)
     end
   end
 end
diff --git a/lib/vaporware/compiler/generator.rb b/lib/vaporware/compiler/generator.rb
index 2fd562a..8eb8708 100644
--- a/lib/vaporware/compiler/generator.rb
+++ b/lib/vaporware/compiler/generator.rb
@@ -30,16 +30,22 @@ def register_var_and_method(node)
       def already_build_methods? = defined_methods.sort == @doned.to_a.sort
       def variable_or_method?(type) = [:lvasgn, :arg, :def].include?(type)
 
-      def call_compiler(output: precompile, compiler: "gcc", compiler_options: ["-O0"], debug: false)
-        base_name = File.basename(output, ".*")
+      def to_elf(input: precompile, compiler: "gcc", compiler_options: ["-O0"], debug: false)
+        base_name = File.basename(input, ".*")
         name = shared ? "lib#{base_name}.so" : base_name
-        compile_commands = [compiler, *compiler_options, "-o", name, output].compact
-        IO.popen(compile_commands).close
+        if compiler.nil?
+          Vaporware::Compiler::Assemble.compile!(name, input)
+        else
+          compile_commands = [compiler, *compiler_options, "-o", name, input].compact
+          call_compiler(compile_commands)
+        end
 
-        File.delete(output) unless debug
+        File.delete(input) unless debug
         nil
       end
 
+      def call_compiler(compile_commands) = IO.popen(compile_commands).close
+
       def epilogue(output)
         output.puts "  mov rsp, rbp"
         output.puts "  pop rbp"
diff --git a/sig/vaporware.rbs b/sig/vaporware.rbs
index d96a8ee..3e9535e 100644
--- a/sig/vaporware.rbs
+++ b/sig/vaporware.rbs
@@ -39,7 +39,7 @@ module Vaporware
       def already_build_methods?: -> bool
       def args: (untyped, File) -> nil
       def build: (untyped, File, ?bool) -> nil
-      def call_compiler: (?output: String, ?compiler: String, ?compiler_options: Array[String], ?debug: bool) -> nil
+      def call_compiler: (Array[String]) -> nil
       def call_method: (untyped, File, bool) -> nil
       def comp: (String, File) -> nil
       def compile_shared_option: () -> Array[String]
@@ -52,6 +52,7 @@ module Vaporware
       def ret: (File) -> nil
       def lvar_offset: (Symbol | nil) -> Integer
       def register_var_and_method: (untyped) -> nil
+      def to_elf: (?input: String, ?compiler: String, ?compiler_options: Array[String], ?debug: bool) -> nil
       def variable_or_method?: (Symbol) -> bool
     end
   end