diff --git a/lib/git_ops/version_replace.ex b/lib/git_ops/version_replace.ex
index 0d94d87..9a9dd16 100644
--- a/lib/git_ops/version_replace.ex
+++ b/lib/git_ops/version_replace.ex
@@ -10,8 +10,20 @@ defmodule GitOps.VersionReplace do
     update_file(file, "@version \"#{current_version}\"", "@version \"#{new_version}\"", opts)
   end
 
-  @spec update_readme(String.t(), String.t(), String.t()) :: String.t() | {:error, :bad_replace}
-  def update_readme(readme, current_version, new_version, opts \\ []) do
+  @spec update_readme(
+          String.t()
+          | {String.t(), fun :: (String.t() -> String.t()), fun :: (String.t() -> String.t())},
+          String.t(),
+          String.t()
+        ) :: String.t() | {:error, :bad_replace}
+  def update_readme(readme, current_version, new_version, opts \\ [])
+
+  def update_readme({readme, replace, pattern}, current_version, new_version, opts)
+      when is_function(replace, 1) and is_function(pattern, 1) do
+    update_file(readme, replace.(current_version), pattern.(new_version), opts)
+  end
+
+  def update_readme(readme, current_version, new_version, opts) do
     update_file(readme, ", \"~> #{current_version}\"", ", \"~> #{new_version}\"", opts)
   end
 
diff --git a/test/version_replace_test.exs b/test/version_replace_test.exs
index 24d85ee..96fb015 100644
--- a/test/version_replace_test.exs
+++ b/test/version_replace_test.exs
@@ -22,6 +22,14 @@ defmodule GitOps.Test.VersionReplaceTest do
     """
   end
 
+  def package_json_contents(version) do
+    """
+    {
+      "version": "#{version}"
+    }
+    """
+  end
+
   setup do
     readme = "TEST_README.md"
     version = "0.1.1"
@@ -30,9 +38,15 @@ defmodule GitOps.Test.VersionReplaceTest do
 
     File.write!(readme, readme_contents)
 
-    on_exit(fn -> File.rm!(readme) end)
+    package_json = "package.json"
+    File.write!(package_json, package_json_contents(version))
+
+    on_exit(fn ->
+      File.rm!(readme)
+      File.rm!(package_json)
+    end)
 
-    %{readme: readme, version: version}
+    %{readme: readme, package_json: package_json, version: version}
   end
 
   test "that README gets written to properly", context do
@@ -54,4 +68,18 @@ defmodule GitOps.Test.VersionReplaceTest do
 
     assert File.read!(readme) == readme_contents(version)
   end
+
+  test "custom replace/pattern", context do
+    readme = context.package_json
+    version = context.version
+    new_version = "1.0.0"
+
+    VersionReplace.update_readme(
+      {readme, fn v -> "\"version\": \"#{v}\"" end, fn v -> "\"version\": \"#{v}\"" end},
+      version,
+      new_version
+    )
+
+    assert File.read!(readme) == package_json_contents(new_version)
+  end
 end