diff --git a/CHANGELOG.md b/CHANGELOG.md
index d5457010..d179d5ab 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## v2.5.1-dev
 
+### Bug fixes
+
+* Remove regexes from compiled code. Compiled regex patterns are not portable across OTP versions, so the precompiled archive could crash with `:re.import/1 is undefined` when built and run on different OTP versions
+
 ## v2.5.0 (2026-06-28)
 
 ### Enhancements
diff --git a/lib/hex/cooldown.ex b/lib/hex/cooldown.ex
index ece91156..53b93d8c 100644
--- a/lib/hex/cooldown.ex
+++ b/lib/hex/cooldown.ex
@@ -70,15 +70,16 @@ defmodule Hex.Cooldown do
   @spec duration_to_seconds(String.t()) :: {:ok, non_neg_integer()} | :error
   def duration_to_seconds("0"), do: {:ok, 0}
 
-  def duration_to_seconds(string) when is_binary(string) do
-    with [_, digits, unit] <- Regex.run(~r/\A(\d+)(d|w|mo)\z/, string),
-         {n, ""} <- Integer.parse(digits) do
-      {:ok, n * unit_seconds(unit)}
-    else
+  # The leading-digit guard rejects the signs Integer.parse/1 accepts ("+5d", "-5d")
+  def duration_to_seconds(<<digit, _::binary>> = string) when digit in ?0..?9 do
+    case Integer.parse(string) do
+      {n, unit} when unit in ["d", "w", "mo"] -> {:ok, n * unit_seconds(unit)}
       _ -> :error
     end
   end
 
+  def duration_to_seconds(string) when is_binary(string), do: :error
+
   defp unit_seconds("d"), do: 86_400
   defp unit_seconds("w"), do: 86_400 * 7
   defp unit_seconds("mo"), do: 86_400 * 30
diff --git a/lib/mix/tasks/hex.build.ex b/lib/mix/tasks/hex.build.ex
index 2c91011b..453e93d8 100644
--- a/lib/mix/tasks/hex.build.ex
+++ b/lib/mix/tasks/hex.build.ex
@@ -251,13 +251,14 @@ defmodule Mix.Tasks.Hex.Build do
   @doc false
   def package(package, config) do
     files = package[:files] || Hex.Package.default_files()
-    exclude_patterns = (package[:exclude_patterns] || []) ++ [~r/\W\.DS_Store$/]
+    exclude_patterns = package[:exclude_patterns] || []
 
     files =
       files
       |> expand_paths(File.cwd!())
       |> Enum.reject(fn path ->
-        Enum.any?(exclude_patterns, &(path =~ &1))
+        Path.basename(path) == ".DS_Store" or
+          Enum.any?(exclude_patterns, &(path =~ &1))
       end)
 
     package
diff --git a/test/hex/cooldown_test.exs b/test/hex/cooldown_test.exs
index e61059b6..dd9ad15d 100644
--- a/test/hex/cooldown_test.exs
+++ b/test/hex/cooldown_test.exs
@@ -37,6 +37,21 @@ defmodule Hex.CooldownTest do
       assert {:ok, 14 * 86_400} == Cooldown.duration_to_seconds("2w")
       assert {:ok, 30 * 86_400} == Cooldown.duration_to_seconds("1mo")
     end
+
+    test "rejects malformed durations" do
+      assert :error == Cooldown.duration_to_seconds("")
+      assert :error == Cooldown.duration_to_seconds("5")
+      assert :error == Cooldown.duration_to_seconds("00")
+      assert :error == Cooldown.duration_to_seconds("d")
+      assert :error == Cooldown.duration_to_seconds("5m")
+      assert :error == Cooldown.duration_to_seconds("5x")
+      assert :error == Cooldown.duration_to_seconds("5dd")
+      assert :error == Cooldown.duration_to_seconds("+5d")
+      assert :error == Cooldown.duration_to_seconds("-5d")
+      assert :error == Cooldown.duration_to_seconds("1_0d")
+      assert :error == Cooldown.duration_to_seconds(" 5d")
+      assert :error == Cooldown.duration_to_seconds("5d ")
+    end
   end
 
   describe "build_cutoff/0" do
diff --git a/test/hex/no_regex_test.exs b/test/hex/no_regex_test.exs
new file mode 100644
index 00000000..d8d86772
--- /dev/null
+++ b/test/hex/no_regex_test.exs
@@ -0,0 +1,23 @@
+defmodule Hex.NoRegexTest do
+  use ExUnit.Case, async: true
+
+  # Compiled regexes are embedded into beam files, and the compiled PCRE
+  # pattern format is not portable across OTP versions (for example,
+  # :re.import/1 does not exist before OTP 28.1). The Hex archive is
+  # precompiled once and installed on many OTP versions, so code under
+  # lib/ must not use regexes; parse with pattern matching instead.
+  test "lib/ contains no regexes" do
+    paths = Path.wildcard("lib/**/*.ex")
+    assert paths != []
+
+    offenders =
+      Enum.filter(paths, fn path ->
+        content = File.read!(path)
+        String.contains?(content, ["~r", "~R", "Regex.", ":re."])
+      end)
+
+    assert offenders == [],
+           "Regex usage found in shipped code: #{inspect(offenders)}. " <>
+             "Regexes must not appear under lib/, see comment in #{__ENV__.file}"
+  end
+end
diff --git a/test/mix/tasks/hex.build_test.exs b/test/mix/tasks/hex.build_test.exs
index a4e2938d..8d24f254 100644
--- a/test/mix/tasks/hex.build_test.exs
+++ b/test/mix/tasks/hex.build_test.exs
@@ -149,6 +149,7 @@ defmodule Mix.Tasks.Hex.BuildTest do
       File.write!("myfile.txt", "hello")
       File.write!("executable.sh", "world")
       File.write!("dir/dir2/test.txt", "and")
+      File.write!("dir/.DS_Store", "junk")
       File.chmod!("myfile.txt", 0o100644)
       File.chmod!("executable.sh", 0o100755)
       File.chmod!("dir/dir2/test.txt", 0o100644)
@@ -170,6 +171,7 @@ defmodule Mix.Tasks.Hex.BuildTest do
       assert File.read!("unzip/myfile.txt") == "hello"
       assert File.read!("unzip/dir/.dotfile") == ""
       assert File.read!("unzip/dir/dir2/test.txt") == "and"
+      refute File.exists?("unzip/dir/.DS_Store")
       assert File.stat!("unzip/myfile.txt").mode == 0o100644
       assert File.stat!("unzip/executable.sh").mode == 0o100755
     end)