diff --git a/lib/ruby_vm/rjit/insn_compiler.rb b/lib/ruby_vm/rjit/insn_compiler.rb
index 376902553e88b0..aff61afc65faac 100644
--- a/lib/ruby_vm/rjit/insn_compiler.rb
+++ b/lib/ruby_vm/rjit/insn_compiler.rb
@@ -18,7 +18,7 @@ def compile(jit, ctx, asm, insn)
       asm.incr_counter(:rjit_insns_count)
       asm.comment("Insn: #{insn.name}")
 
-      # 77/102
+      # 78/102
       case insn.name
       when :nop then nop(jit, ctx, asm)
       when :getlocal then getlocal(jit, ctx, asm)
@@ -66,7 +66,7 @@ def compile(jit, ctx, asm, insn)
       when :defined then defined(jit, ctx, asm)
       when :definedivar then definedivar(jit, ctx, asm)
       # checkmatch
-      # checkkeyword
+      when :checkkeyword then checkkeyword(jit, ctx, asm)
       # checktype
       # defineclass
       # definemethod
@@ -1154,7 +1154,43 @@ def definedivar(jit, ctx, asm)
     end
 
     # checkmatch
-    # checkkeyword
+
+    def checkkeyword(jit, ctx, asm)
+      # When a keyword is unspecified past index 32, a hash will be used
+      # instead. This can only happen in iseqs taking more than 32 keywords.
+      if jit.iseq.body.param.keyword.num >= 32
+        return CantCompile
+      end
+
+      # The EP offset to the undefined bits local
+      bits_offset = jit.operand(0)
+
+      # The index of the keyword we want to check
+      index = jit.operand(1, signed: true)
+
+      # Load environment pointer EP
+      ep_reg = :rax
+      jit_get_ep(asm, 0, reg: ep_reg)
+
+      # VALUE kw_bits = *(ep - bits)
+      bits_opnd = [ep_reg, C.VALUE.size * -bits_offset]
+
+      # unsigned int b = (unsigned int)FIX2ULONG(kw_bits);
+      # if ((b & (0x01 << idx))) {
+      #
+      # We can skip the FIX2ULONG conversion by shifting the bit we test
+      bit_test = 0x01 << (index + 1)
+      asm.test(bits_opnd, bit_test)
+      asm.mov(:rax, Qfalse)
+      asm.mov(:rcx, Qtrue)
+      asm.cmovz(:rax, :rcx)
+
+      stack_ret = ctx.stack_push
+      asm.mov(stack_ret, :rax)
+
+      KeepCompiling
+    end
+
     # checktype
     # defineclass
     # definemethod
diff --git a/rjit_c.rb b/rjit_c.rb
index 677e294ddb9bb9..32731ba4d0db06 100644
--- a/rjit_c.rb
+++ b/rjit_c.rb
@@ -1001,6 +1001,18 @@ def C.rb_iseq_location_t
     )
   end
 
+  def C.rb_iseq_param_keyword
+    @rb_iseq_param_keyword ||= CType::Struct.new(
+      "rb_iseq_param_keyword", Primitive.cexpr!("SIZEOF(struct rb_iseq_param_keyword)"),
+      num: [CType::Immediate.parse("int"), Primitive.cexpr!("OFFSETOF((*((struct rb_iseq_param_keyword *)NULL)), num)")],
+      required_num: [CType::Immediate.parse("int"), Primitive.cexpr!("OFFSETOF((*((struct rb_iseq_param_keyword *)NULL)), required_num)")],
+      bits_start: [CType::Immediate.parse("int"), Primitive.cexpr!("OFFSETOF((*((struct rb_iseq_param_keyword *)NULL)), bits_start)")],
+      rest_start: [CType::Immediate.parse("int"), Primitive.cexpr!("OFFSETOF((*((struct rb_iseq_param_keyword *)NULL)), rest_start)")],
+      table: [CType::Pointer.new { self.ID }, Primitive.cexpr!("OFFSETOF((*((struct rb_iseq_param_keyword *)NULL)), table)")],
+      default_values: [CType::Pointer.new { self.VALUE }, Primitive.cexpr!("OFFSETOF((*((struct rb_iseq_param_keyword *)NULL)), default_values)")],
+    )
+  end
+
   def C.rb_iseq_struct
     @rb_iseq_struct ||= CType::Struct.new(
       "rb_iseq_struct", Primitive.cexpr!("SIZEOF(struct rb_iseq_struct)"),
@@ -1354,10 +1366,6 @@ def C.rb_iseq_type
     CType::Stub.new(:rb_iseq_type)
   end
 
-  def C.rb_iseq_param_keyword
-    CType::Stub.new(:rb_iseq_param_keyword)
-  end
-
   def C.iseq_insn_info
     CType::Stub.new(:iseq_insn_info)
   end
diff --git a/tool/rjit/bindgen.rb b/tool/rjit/bindgen.rb
index bcc4ee954a7d90..ad2e5f9e1e3252 100755
--- a/tool/rjit/bindgen.rb
+++ b/tool/rjit/bindgen.rb
@@ -156,8 +156,8 @@ def generate(nodes)
       println
     end
 
-    # TODO: Support nested declarations
-    nodes_index = nodes.group_by(&:spelling).transform_values do |values|
+    # Build a hash table for type lookup by name
+    nodes_index = flatten_nodes(nodes).group_by(&:spelling).transform_values do |values|
       # Try to search a declaration with definitions
       node_with_children = values.find { |v| !v.children.empty? }
       next node_with_children if node_with_children
@@ -169,7 +169,7 @@ def generate(nodes)
     # Define types
     @types.each do |type|
       unless definition = generate_node(nodes_index[type])
-        raise "Failed to generate type: #{type}"
+        raise "Failed to find or generate type: #{type}"
       end
       println "  def C.#{type}"
       println "@#{type} ||= #{definition}".gsub(/^/, "    ").chomp
@@ -201,6 +201,18 @@ def generate(nodes)
 
   private
 
+  # Make an array that includes all top-level and nested nodes
+  def flatten_nodes(nodes)
+    result = []
+    nodes.each do |node|
+      unless node.children.empty?
+        result.concat(flatten_nodes(node.children))
+      end
+    end
+    result.concat(nodes) # prioritize top-level nodes
+    result
+  end
+
   # Return code before BINDGEN_BEG and code after BINDGEN_END
   def split_ambles(src_path)
     lines = File.read(src_path).lines
@@ -573,6 +585,7 @@ def push_target(target)
     rb_shape_t
     rb_thread_struct
     rb_jit_func_t
+    rb_iseq_param_keyword
     rjit_options
   ],
   # #ifdef-dependent immediate types, which need Primitive.cexpr! for type detection