diff --git a/lib/typeprof/core/ast/misc.rb b/lib/typeprof/core/ast/misc.rb
index cf69b92b7..9c94bc5ed 100644
--- a/lib/typeprof/core/ast/misc.rb
+++ b/lib/typeprof/core/ast/misc.rb
@@ -265,19 +265,39 @@ def install0(genv)
     class ForNode < Node
       def initialize(raw_node, lenv)
         super(raw_node, lenv)
-        # XXX: tentative implementation
-        # raw_node.index
+        @index = AST.create_target_node(raw_node.index, lenv)
         @expr = AST.create_node(raw_node.collection, lenv)
         @body = raw_node.statements ? AST.create_node(raw_node.statements, lenv) : DummyNilNode.new(TypeProf::CodeRange.new(code_range.last, code_range.last), lenv)
       end
 
-      attr_reader :expr, :body
+      attr_reader :index, :expr, :body
 
-      def subnodes = { expr:, body: }
+      def subnodes = { index:, expr:, body: }
 
       def install0(genv)
         @expr.install(genv)
+
+        vars = []
+        @index.modified_vars(@lenv.locals.keys, vars)
+        @body.modified_vars(@lenv.locals.keys, vars)
+        vars.uniq!
+
+        old_vtxs = {}
+        vars.each do |var|
+          vtx = @lenv.get_var(var)
+          nvtx = vtx.new_vertex(genv, self)
+          old_vtxs[var] = nvtx
+          @lenv.set_var(var, nvtx)
+        end
+
+        @index.install(genv)
         @body.install(genv)
+
+        vars.each do |var|
+          @changes.add_edge(genv, @lenv.get_var(var), old_vtxs[var])
+          @lenv.set_var(var, old_vtxs[var])
+        end
+
         Source.new(genv.nil_type)
       end
     end
diff --git a/lib/typeprof/core/env.rb b/lib/typeprof/core/env.rb
index 6da8d0b2d..911174687 100644
--- a/lib/typeprof/core/env.rb
+++ b/lib/typeprof/core/env.rb
@@ -333,8 +333,6 @@ def initialize(file_context, cref, locals, return_boxes)
     attr_reader :file_context, :cref, :locals, :return_boxes, :break_vtx, :next_boxes, :strict_const_scope
 
     def path = @file_context&.path
-    def code_units_cache = @file_context&.code_units_cache
-
     def code_range_from_node(node)
       TypeProf::CodeRange.from_node(node, @file_context&.code_units_cache)
     end
diff --git a/scenario/misc/for-variable-leak.rb b/scenario/misc/for-variable-leak.rb
new file mode 100644
index 000000000..2a04d1f72
--- /dev/null
+++ b/scenario/misc/for-variable-leak.rb
@@ -0,0 +1,13 @@
+## update
+def foo
+  x = "hello"
+  for i in [1, 2, 3]
+    x = 42
+  end
+  x
+end
+
+## assert
+class Object
+  def foo: -> (Integer | String)
+end
diff --git a/scenario/misc/for.rb b/scenario/misc/for.rb
index e4fc8e011..718dd2dfc 100644
--- a/scenario/misc/for.rb
+++ b/scenario/misc/for.rb
@@ -1,7 +1,6 @@
 ## update
 def foo
   for i in 1..100
-    # currently, TypeProf does not initialize i
     return 1
   end
 end