diff --git a/lib/ruby_vm/rjit/insn_compiler.rb b/lib/ruby_vm/rjit/insn_compiler.rb
index 86983bdc3f..162b8c2eb5 100644
--- a/lib/ruby_vm/rjit/insn_compiler.rb
+++ b/lib/ruby_vm/rjit/insn_compiler.rb
@@ -200,7 +200,7 @@ module RubyVM::RJIT
       asm.mov(C_ARGS[0], EC)
       # The block handler for the current frame
       # note, VM_ASSERT(VM_ENV_LOCAL_P(ep))
-      asm.mov(C_ARGS[1], [ep_reg, C.VALUE.size * C.VM_ENV_DATA_INDEX_SPECVAL])
+      asm.mov(C_ARGS[1], [ep_reg, C.VALUE.size * C::VM_ENV_DATA_INDEX_SPECVAL])
       asm.call(C.rb_vm_bh_to_procval)
 
       # Load environment pointer EP from CFP (again)
@@ -271,7 +271,7 @@ module RubyVM::RJIT
       # Load the block handler for the current frame
       # note, VM_ASSERT(VM_ENV_LOCAL_P(ep))
       block_handler = :rax
-      asm.mov(block_handler, [ep_reg, C.VALUE.size * C.VM_ENV_DATA_INDEX_SPECVAL])
+      asm.mov(block_handler, [ep_reg, C.VALUE.size * C::VM_ENV_DATA_INDEX_SPECVAL])
 
       # Specialize compilation for the case where no block handler is present
       if comptime_handler == 0
@@ -2821,7 +2821,7 @@ module RubyVM::RJIT
       asm.mov(reg, [CFP, C.rb_control_frame_t.offsetof(:ep)])
       level.times do
         # GET_PREV_EP: ep[VM_ENV_DATA_INDEX_SPECVAL] & ~0x03
-        asm.mov(reg, [reg, C.VALUE.size * C.VM_ENV_DATA_INDEX_SPECVAL])
+        asm.mov(reg, [reg, C.VALUE.size * C::VM_ENV_DATA_INDEX_SPECVAL])
         asm.and(reg, ~0x03)
       end
     end
@@ -2965,7 +2965,7 @@ module RubyVM::RJIT
           # Guard no block passed. Only handle that case for now.
           asm.comment('guard no block given')
           jit_get_lep(jit, asm, reg: :rax)
-          asm.cmp([:rax, C.VALUE.size * C.VM_ENV_DATA_INDEX_SPECVAL], C.VM_BLOCK_HANDLER_NONE)
+          asm.cmp([:rax, C.VALUE.size * C::VM_ENV_DATA_INDEX_SPECVAL], C.VM_BLOCK_HANDLER_NONE)
           asm.jne(counted_exit(side_exit, :send_block_handler))
           return C.VM_BLOCK_HANDLER_NONE
         else
@@ -3092,7 +3092,7 @@ module RubyVM::RJIT
       jit_get_lep(jit, asm, reg: :rax)
 
       asm.mov(:rcx, me.to_i)
-      asm.cmp([:rax, C.VALUE.size * C.VM_ENV_DATA_INDEX_ME_CREF], :rcx)
+      asm.cmp([:rax, C.VALUE.size * C::VM_ENV_DATA_INDEX_ME_CREF], :rcx)
       asm.jne(counted_exit(side_exit, :invokesuper_me_changed))
 
       # We need to assume that both our current method entry and the super
@@ -3711,7 +3711,7 @@ module RubyVM::RJIT
         #   VALUE handler = VM_CF_BLOCK_HANDLER(reg_cfp);
         #   reg_cfp->block_code = (const void *) handler;
         jit_get_lep(jit, asm, reg: :rax)
-        asm.mov(:rax, [:rax, C.VALUE.size * C.VM_ENV_DATA_INDEX_SPECVAL]) # handler
+        asm.mov(:rax, [:rax, C.VALUE.size * C::VM_ENV_DATA_INDEX_SPECVAL]) # handler
         asm.mov([CFP, C.rb_control_frame_t.offsetof(:block_code)], :rax)
 
         asm.mov(:rax, C.rb_block_param_proxy)
diff --git a/lib/ruby_vm/rjit/jit_state.rb b/lib/ruby_vm/rjit/jit_state.rb
index 6becee19f7..a365559d17 100644
--- a/lib/ruby_vm/rjit/jit_state.rb
+++ b/lib/ruby_vm/rjit/jit_state.rb
@@ -40,7 +40,7 @@ module RubyVM::RJIT
 
     def peek_at_block_handler(level)
       ep = ep_at_level(cfp, level:)
-      ep[C.VM_ENV_DATA_INDEX_SPECVAL]
+      ep[C::VM_ENV_DATA_INDEX_SPECVAL]
     end
 
     private
@@ -49,7 +49,7 @@ module RubyVM::RJIT
       ep = cfp.ep
       level.times do
         # VM_ENV_PREV_EP
-        ep = C.VALUE.new(ep[C.VM_ENV_DATA_INDEX_SPECVAL] & ~0x03)
+        ep = C.VALUE.new(ep[C::VM_ENV_DATA_INDEX_SPECVAL] & ~0x03)
       end
       ep
     end
diff --git a/rjit_c.rb b/rjit_c.rb
index 6e4c05bc87..7f510f2014 100644
--- a/rjit_c.rb
+++ b/rjit_c.rb
@@ -2,9 +2,9 @@
 # Part of this file is generated by tool/rjit/bindgen.rb.
 # Run `make rjit-bindgen` to update code between "RJIT bindgen begin" and "RJIT bindgen end".
 module RubyVM::RJIT # :nodoc: all
-  # This `class << C` section is for calling C functions. For importing variables
-  # or macros as is, please consider using tool/rjit/bindgen.rb instead.
-  class << C = Object.new
+  # This `class << C` section is for calling C functions with Primitive.
+  # For importing variables or macros, use tool/rjit/bindgen.rb instead.
+  class << C = Module.new
     def mmap(mem_size)
       Primitive.cexpr! 'SIZET2NUM((size_t)rjit_reserve_addr_space(NUM2UINT(mem_size)))'
     end
@@ -312,13 +312,8 @@ module RubyVM::RJIT # :nodoc: all
 
   ### RJIT bindgen begin ###
 
-  def C.VM_ENV_DATA_INDEX_ME_CREF
-    Primitive.cexpr! %q{ LONG2NUM(VM_ENV_DATA_INDEX_ME_CREF) }
-  end
-
-  def C.VM_ENV_DATA_INDEX_SPECVAL
-    Primitive.cexpr! %q{ LONG2NUM(VM_ENV_DATA_INDEX_SPECVAL) }
-  end
+  C::VM_ENV_DATA_INDEX_ME_CREF = Primitive.cexpr! %q{ LONG2NUM(VM_ENV_DATA_INDEX_ME_CREF) }
+  C::VM_ENV_DATA_INDEX_SPECVAL = Primitive.cexpr! %q{ LONG2NUM(VM_ENV_DATA_INDEX_SPECVAL) }
 
   def C.ARRAY_REDEFINED_OP_FLAG
     Primitive.cexpr! %q{ SIZET2NUM(ARRAY_REDEFINED_OP_FLAG) }
diff --git a/tool/mk_builtin_loader.rb b/tool/mk_builtin_loader.rb
index fc6900808f..ba5e3c1ad7 100644
--- a/tool/mk_builtin_loader.rb
+++ b/tool/mk_builtin_loader.rb
@@ -265,7 +265,8 @@ def generate_cexpr(ofile, lineno, line_file, body_lineno, text, locals, func_nam
   f = StringIO.new
   f.puts '{'
   lineno += 1
-  locals.reverse_each.with_index{|param, i|
+  # locals is nil outside methods
+  locals&.reverse_each&.with_index{|param, i|
     next unless Symbol === param
     f.puts "MAYBE_UNUSED(const VALUE) #{param} = rb_vm_lvar(ec, #{-3 - i});"
     lineno += 1
diff --git a/tool/rjit/bindgen.rb b/tool/rjit/bindgen.rb
index abff60fdc3..a34ac9649b 100755
--- a/tool/rjit/bindgen.rb
+++ b/tool/rjit/bindgen.rb
@@ -106,15 +106,17 @@ class BindingGenerator
   attr_reader :src
 
   # @param src_path [String]
+  # @param consts [Hash{ Symbol => Array<String> }]
   # @param values [Hash{ Symbol => Array<String> }]
   # @param funcs [Array<String>]
   # @param types [Array<String>]
   # @param dynamic_types [Array<String>] #ifdef-dependent immediate types, which need Primitive.cexpr! for type detection
   # @param skip_fields [Hash{ Symbol => Array<String> }] Struct fields that are skipped from bindgen
   # @param ruby_fields [Hash{ Symbol => Array<String> }] Struct VALUE fields that are considered Ruby objects
-  def initialize(src_path:, values:, funcs:, types:, dynamic_types:, skip_fields:, ruby_fields:)
+  def initialize(src_path:, consts:, values:, funcs:, types:, dynamic_types:, skip_fields:, ruby_fields:)
     @preamble, @postamble = split_ambles(src_path)
     @src = String.new
+    @consts = consts.transform_values(&:sort)
     @values = values.transform_values(&:sort)
     @funcs = funcs.sort
     @types = types.sort
@@ -128,6 +130,15 @@ class BindingGenerator
     println @preamble
 
     # Define macros/enums
+    @consts.each do |type, values|
+      values.each do |value|
+        raise "#{value} isn't a valid constant name" unless ('A'..'Z').include?(value[0])
+        println "  C::#{value} = Primitive.cexpr! %q{ #{type}2NUM(#{value}) }"
+      end
+    end
+    println
+
+    # Define variables
     @values.each do |type, values|
       values.each do |value|
         println "  def C.#{value}"
@@ -137,6 +148,7 @@ class BindingGenerator
       end
     end
 
+    # Define function pointers
     @funcs.each do |func|
       println "  def C.#{func}"
       println "    Primitive.cexpr! %q{ SIZET2NUM((size_t)#{func}) }"
@@ -351,11 +363,13 @@ end
 nodes = HeaderParser.new(File.join(src_dir, 'rjit_c.h'), cflags: cflags).parse
 generator = BindingGenerator.new(
   src_path: src_path,
-  values: {
+  consts: {
     LONG: %w[
       VM_ENV_DATA_INDEX_ME_CREF
       VM_ENV_DATA_INDEX_SPECVAL
     ],
+  },
+  values: {
     SIZET: %w[
       ARRAY_REDEFINED_OP_FLAG
       BOP_AND