diff --git a/lib/ex_factor/callers.ex b/lib/ex_factor/callers.ex
index e4c38f2..f95389c 100644
--- a/lib/ex_factor/callers.ex
+++ b/lib/ex_factor/callers.ex
@@ -12,10 +12,11 @@ defmodule ExFactor.Callers do
   use `mix xref` list all the callers of a given module.
   """
   def callers(mod) do
-    capture_io(fn -> Mix.Tasks.Xref.run(["callers", mod]) end)
-    |> String.trim()
-    |> String.split("\n")
-    |> mangle_list()
+    Mix.Tasks.Xref.calls([])
+    |> Enum.filter(fn x ->
+      module = cast(mod)
+      match?({^module, _, _}, x.callee)
+    end)
   end
 
   def callers(mod, func, arity) do
@@ -53,7 +54,10 @@ defmodule ExFactor.Callers do
   defp mangle_list(list) do
     Enum.map(list, fn string ->
       [path, type] = String.split(string, " ")
-      %{filepath: path, dependency_type: type}
+      %{
+        file: path,
+        dependency_type: type
+      }
     end)
   end
 end
diff --git a/lib/ex_factor/changer.ex b/lib/ex_factor/changer.ex
index 6d477dd..db49495 100644
--- a/lib/ex_factor/changer.ex
+++ b/lib/ex_factor/changer.ex
@@ -6,6 +6,21 @@ defmodule ExFactor.Changer do
 
   alias ExFactor.Callers
 
+  @doc """
+  Given all the Callers of a module, find the instances of usage of the module and refactor the
+  module reference to the new module. Respect any existing aliases.
+  """
+  def rename_module(opts) do
+    Mix.Tasks.Compile.Elixir.run([])
+    :timer.sleep(100)
+    source_module = Keyword.fetch!(opts, :source_module)
+
+    source_module
+    |> Callers.callers()
+    |> Enum.group_by(& &1.file)
+    |> update_caller_module(opts)
+  end
+
   @doc """
   Given all the Callers to a module, find the instances of the target function and refactor the
   function module reference to the new module. Respect any existing aliases.
@@ -31,6 +46,24 @@ defmodule ExFactor.Changer do
     [%ExFactor{state: [:unchanged], message: "No additional references to source module: (#{source_module}) detected"}]
   end
 
+  defp update_caller_module(callers, opts) do
+    dry_run = Keyword.get(opts, :dry_run, false)
+
+    Enum.map(callers, fn {file, [first | _] = grouped_callers} ->
+      file_list =
+        File.read!(file)
+        |> String.split("\n")
+
+      grouped_callers
+      |> Enum.reduce({[:unchanged], file_list}, fn %{line: line}, acc ->
+        find_and_replace_module(acc, opts, line)
+      end)
+      |> maybe_add_import(opts)
+      |> maybe_add_alias(opts)
+      |> write_file(first.caller_module, file, dry_run)
+    end)
+  end
+
   defp update_caller_groups(callers, opts) do
     dry_run = Keyword.get(opts, :dry_run, false)
 
@@ -87,6 +120,43 @@ defmodule ExFactor.Changer do
     {new_state, List.replace_at(file_list, line - 1, new_line)}
   end
 
+  defp find_and_replace_module({state, file_list}, opts, line) do
+    # opts values
+    source_module = Keyword.fetch!(opts, :source_module)
+    target_module = Keyword.fetch!(opts, :target_module)
+
+    # modified values
+    source_string = to_string(source_module)
+    source_modules = String.split(source_module, ".")
+    source_alias = Enum.at(source_modules, -1)
+    target_alias = preferred_alias(file_list, target_module)
+    source_alias_alt = find_alias_as(file_list, source_module)
+    fn_line = Enum.at(file_list, line - 1)
+
+    {new_state, new_line} =
+      cond do
+        # match full module name
+        String.match?(fn_line, ~r/#{source_string}/) ->
+          fn_line = String.replace(fn_line, source_module, target_alias)
+          {set_state(state, :changed), fn_line}
+
+        # match aliased module name
+        String.match?(fn_line, ~r/#{source_alias}/) ->
+          fn_line = String.replace(fn_line, source_alias, target_alias)
+          {set_state(state, :changed), fn_line}
+
+        # match module name aliased :as
+        String.match?(fn_line, ~r/#{source_alias_alt}/) ->
+          fn_line = String.replace(fn_line, source_alias_alt, target_alias)
+          {set_state(state, :changed), fn_line}
+
+        true ->
+          {state, fn_line}
+      end
+
+    {new_state, List.replace_at(file_list, line - 1, new_line)}
+  end
+
   defp find_alias_as(list, module) do
     aalias = Enum.find(list, "", fn el -> str_match?(el, module) end)
 
diff --git a/test/ex_factor/callers_test.exs b/test/ex_factor/callers_test.exs
index ead2290..2bb913e 100644
--- a/test/ex_factor/callers_test.exs
+++ b/test/ex_factor/callers_test.exs
@@ -4,11 +4,12 @@ defmodule ExFactor.CallersTest do
 
   describe "callers/1" do
     test "it should report callers of a module" do
-      [one, _two, _three, _four, five] = Callers.callers(ExFactor.Parser)
+      callers = Callers.callers(ExFactor.Parser)
 
-      assert one.dependency_type == "(runtime)"
-      assert one.filepath == "lib/ex_factor/callers.ex"
-      assert five.filepath == "test/support/support.ex"
+      assert Enum.find(callers, fn caller -> caller.file == "lib/ex_factor/callers.ex" end)
+      %{} = support = Enum.find(callers, fn caller -> caller.file == "test/support/support.ex" end)
+      assert support.caller_module == ExFactor.Support
+      assert support.callee == {ExFactor.Parser, :all_functions, 1}
     end
 
     test "when no callers" do
diff --git a/test/ex_factor/changer_test.exs b/test/ex_factor/changer_test.exs
index ad897ba..2f33ec0 100644
--- a/test/ex_factor/changer_test.exs
+++ b/test/ex_factor/changer_test.exs
@@ -8,6 +8,78 @@ defmodule ExFactor.ChangerTest do
     :ok
   end
 
+  describe "rename_module/1" do
+    test "it renames all the instances of a module" do
+      content = """
+        defmodule ExFactor.Tmp.SourceMod do
+          def refactor1(_), do: :ok
+        end
+      """
+
+      File.write("lib/ex_factor/tmp/source_module.ex", content)
+
+      content = """
+      defmodule ExFactor.Tmp.CallerModule do
+        @moduledoc \"\"\"
+        This is a multiline moduedoc.
+        Its in the caller module
+        \"\"\"
+        alias ExFactor.Tmp.SourceMod
+        alias ExFactor.Tmp.SourceMod.Other
+        def pub1(arg_a) do
+          SourceMod.refactor1(arg_a)
+        end
+        def pub2, do: Other
+
+        def pub3(arg_a) do
+          SourceMod.refactor1(arg_a)
+        end
+      end
+      """
+
+      File.write("lib/ex_factor/tmp/caller_module.ex", content)
+
+      content = """
+      defmodule ExFactor.Tmp.CallerTwoModule do
+        def pub1(arg_a) do
+          ExFactor.Tmp.SourceMod.refactor1(arg_a)
+        end
+        def pub2, do: Enum
+      end
+      """
+
+      File.write("lib/ex_factor/tmp/caller_two_module.ex", content)
+
+      opts = [
+        target_module: "ExFactor.Tmp.TargetModule",
+        source_module: "ExFactor.Tmp.SourceMod"
+      ]
+
+      changes = Changer.rename_module(opts)
+      assert Enum.find(changes, &(&1.path == "lib/ex_factor/tmp/caller_module.ex"))
+      assert Enum.find(changes, &(&1.path == "lib/ex_factor/tmp/caller_two_module.ex"))
+
+      caller = File.read!("lib/ex_factor/tmp/caller_module.ex")
+      assert caller =~ "alias ExFactor.Tmp.TargetModule"
+      # ensure we don't match dumbly
+      assert caller =~ "alias ExFactor.Tmp.SourceMod.Other"
+      refute caller =~ "alias ExFactor.Tmp.TargetModule.Other"
+      # assert the alias doesn't get spliced into the moduledoc
+      refute caller =~ "Its in the caller module\nalias ExFactor.Tmp.TargetModule\n  \""
+      assert caller =~ "TargetModule.refactor1(arg_a)"
+      # asser the function uses the alias
+      refute caller =~ "ExFactor.Tmp.TargetModule.refactor1(arg_a)"
+      assert caller =~ "def pub3(arg_a) do\n    TargetModule.refactor1(arg_a)"
+
+      caller_two = File.read!("lib/ex_factor/tmp/caller_two_module.ex")
+      assert caller_two =~ "alias ExFactor.Tmp.TargetModule"
+      # ensure we don't match dumbly
+      assert caller_two =~ "TargetModule.refactor1(arg_a)"
+      # asser the function uses the alias
+      refute caller_two =~ "ExFactor.Tmp.TargetModule.refactor1(arg_a)"
+    end
+  end
+
   describe "change/1" do
     test "it finds all the callers of a module, function, and arity, and updates the calls to the new module" do
       content = """