diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index f417b1c..1870b05 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -14,7 +14,7 @@ jobs:
       - uses: erlef/setup-beam@v1
         with:
           otp-version: "27"
-          gleam-version: "1.9.0"
+          gleam-version: "1.13.0"
           rebar3-version: "3"
           # elixir-version: "1.14.2"
       - run: gleam test
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5d49b3c..fc448e9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,9 +1,10 @@
 # Changelog
 
-- Add documentation for 'mode' field in FileInfo.
-
 ## Unreleased
 
+## v2.3.2 - 26 December 2025 
+- Fix bug where unknown errors were not properly converted to the Unknown variant in Erlang ffi.
+
 ## v2.3.1 - 6 November 2025 
 - Fix bug with error string typo for `Enotdir` on JS.
 
diff --git a/gleam.toml b/gleam.toml
index 33a959a..b974558 100644
--- a/gleam.toml
+++ b/gleam.toml
@@ -1,5 +1,5 @@
 name = "simplifile"
-version = "2.3.1"
+version = "2.3.2"
 description = "Basic file operations that work on all targets"
 
 licences = ["Apache-2.0"]
diff --git a/src/simplifile_erl.erl b/src/simplifile_erl.erl
index 09bef7a..a1d138f 100644
--- a/src/simplifile_erl.erl
+++ b/src/simplifile_erl.erl
@@ -91,7 +91,9 @@ posix_result(Result) ->
         {ok, Value} ->
             {ok, Value};
         {error, Reason} when ?is_posix_error(Reason) ->
-            {error, Reason}
+            {error, Reason};
+        {error, Reason} ->
+            {error, {unknown, string:uppercase(atom_to_binary(Reason))}}
     end.
 
 %% Read the binary contents of a file
diff --git a/test/simplifile_test.gleam b/test/simplifile_test.gleam
index 48701c6..0cbe3c2 100644
--- a/test/simplifile_test.gleam
+++ b/test/simplifile_test.gleam
@@ -1,21 +1,23 @@
 import gleam/int
 import gleam/list
 import gleam/set
+import gleam/string
 import gleeunit
 import gleeunit/should
 import simplifile.{
-  Directory, Eacces, Eagain, Ebadf, Ebadmsg, Ebusy, Edeadlk, Edeadlock, Edquot,
-  Eexist, Efault, Efbig, Eftype, Einval, Eio, Eisdir, Eloop, Emfile, Emlink,
-  Emultihop, Enametoolong, Enfile, Enobufs, Enodev, Enoent, Enolck, Enolink,
-  Enomem, Enospc, Enosr, Enostr, Enosys, Enotblk, Enotdir, Enotsup, Enxio,
-  Eopnotsupp, Eoverflow, Eperm, Epipe, Erange, Erofs, Espipe, Esrch, Estale,
-  Etxtbsy, Exdev, Execute, File, FilePermissions, NotUtf8, Read, Unknown, Write,
-  append, append_bits, copy, copy_directory, copy_file, create_directory,
-  create_directory_all, create_file, create_link, create_symlink, delete,
-  delete_all, file_info, file_info_permissions, file_info_permissions_octal,
-  file_info_type, file_permissions_to_octal, get_files, is_directory, is_file,
-  is_symlink, link_info, read, read_bits, read_directory, rename,
-  set_permissions, set_permissions_octal, write, write_bits,
+  type FileError, Directory, Eacces, Eagain, Ebadf, Ebadmsg, Ebusy, Edeadlk,
+  Edeadlock, Edquot, Eexist, Efault, Efbig, Eftype, Einval, Eio, Eisdir, Eloop,
+  Emfile, Emlink, Emultihop, Enametoolong, Enfile, Enobufs, Enodev, Enoent,
+  Enolck, Enolink, Enomem, Enospc, Enosr, Enostr, Enosys, Enotblk, Enotdir,
+  Enotsup, Enxio, Eopnotsupp, Eoverflow, Eperm, Epipe, Erange, Erofs, Espipe,
+  Esrch, Estale, Etxtbsy, Exdev, Execute, File, FilePermissions, NotUtf8, Read,
+  Unknown, Write, append, append_bits, copy, copy_directory, copy_file,
+  create_directory, create_directory_all, create_file, create_link,
+  create_symlink, delete, delete_all, file_info, file_info_permissions,
+  file_info_permissions_octal, file_info_type, file_permissions_to_octal,
+  get_files, is_directory, is_file, is_symlink, link_info, read, read_bits,
+  read_directory, rename, set_permissions, set_permissions_octal, write,
+  write_bits,
 }
 
 pub fn main() {
@@ -483,7 +485,9 @@ pub fn file_info_get_permissions_test() {
 pub fn get_files_with_slash_test() {
   let assert Ok(files) = get_files(in: "./test/")
   files
-  |> should.equal(["./test/simplifile_test.gleam"])
+  |> should.equal([
+    "./test/simplifile_test.gleam",
+  ])
 }
 
 // This test is only for local development
@@ -761,3 +765,19 @@ pub fn parse_errors_test() {
     simplifile.create_directory_all("./tmp/wumbo/wombo") |> should.be_error
   err |> should.equal(Enotdir)
 }
+
+pub fn unknown_errors_return_unknown_test() {
+  let err = create_directory_with_bad_arg(#(Nil, Nil))
+  err |> should.be_error
+
+  let assert Error(unknown) = err
+  let assert Unknown(inner) = unknown
+  inner |> should.not_equal("")
+  inner |> string.uppercase |> should.equal(inner)
+  // confirm the string has been uppercased
+}
+
+// This is necessary to force unknown error generation uniformly across runtimes
+@external(erlang, "simplifile_erl", "create_directory")
+@external(javascript, "./simplifile_js.mjs", "createDirectory")
+fn create_directory_with_bad_arg(arg: #(Nil, Nil)) -> Result(Nil, FileError)