diff --git a/.gitignore b/.gitignore
index e88a27a..ff11fa7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,14 +1,14 @@
-# System
-.DS_Store
-
-# Integrated development environment
+# Integrated development environment.
 .vscode
 
-# Package manager
-## Cargo
+# Package manager.
+## Cargo.
 target
-## NPM
+## NPM.
 node_modules
 
-# Test data
+# System.
+.DS_Store
+
+# Test data.
 tmp
diff --git a/.rustfmt.toml b/.rustfmt.toml
index 1b83aba..8a01662 100644
--- a/.rustfmt.toml
+++ b/.rustfmt.toml
@@ -1,18 +1,18 @@
-# Basic
+# Basic.
 edition    = "2021"
 hard_tabs  = true
 max_width  = 100
 tab_spaces = 4
 
-# Imports
+# Import.
 imports_granularity = "Crate"
 reorder_imports     = true
 
-# Format comments
+# Comments.
 comment_width = 100
 wrap_comments = true
 
-# Misc
+# Misc.
 format_code_in_doc_comments = true
 inline_attribute_width      = 100
 match_arm_blocks            = false
diff --git a/Cargo.lock b/Cargo.lock
index bc61060..32954bb 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,57 +1,88 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
+
+[[package]]
+name = "itoa"
+version = "1.0.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d75a2a4b1b190afb6f5425f10f6a8f959d2ea0b9c2b1d79553551850539e4674"
 
 [[package]]
 name = "language"
-version = "0.1.2"
+version = "0.1.3"
 dependencies = [
  "serde",
+ "serde_json",
 ]
 
+[[package]]
+name = "memchr"
+version = "2.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
+
 [[package]]
 name = "proc-macro2"
-version = "1.0.86"
+version = "1.0.92"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5e719e8df665df0d1c8fbfd238015744736151d4445ec0836b8e628aae103b77"
+checksum = "37d3544b3f2748c54e147655edb5025752e2303145b5aefb3c3ea2c78b973bb0"
 dependencies = [
  "unicode-ident",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.36"
+version = "1.0.38"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0fa76aaf39101c457836aec0ce2316dbdc3ab723cdda1c6bd4e6ad4208acaca7"
+checksum = "0e4dccaaaf89514f546c693ddc140f729f958c247918a13380cccc6078391acc"
 dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "ryu"
+version = "1.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f3cb5ba0dc43242ce17de99c180e96db90b235b8a9fdc9543c96d2209116bd9f"
+
 [[package]]
 name = "serde"
-version = "1.0.215"
+version = "1.0.217"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6513c1ad0b11a9376da888e3e0baa0077f1aed55c17f50e7b2397136129fb88f"
+checksum = "02fc4265df13d6fa1d00ecff087228cc0a2b5f3c0e87e258d8b94a156e984c70"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.215"
+version = "1.0.217"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ad1e866f866923f252f05c889987993144fb74e722403468a4ebd70c3cd756c0"
+checksum = "5a9bf7cf98d04a2b28aead066b7496853d4779c9cc183c440dbac457641e19a0"
 dependencies = [
  "proc-macro2",
  "quote",
  "syn",
 ]
 
+[[package]]
+name = "serde_json"
+version = "1.0.135"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b0d7ba2887406110130a978386c4e1befb98c674b4fba677954e4db976630d9"
+dependencies = [
+ "itoa",
+ "memchr",
+ "ryu",
+ "serde",
+]
+
 [[package]]
 name = "syn"
-version = "2.0.82"
+version = "2.0.95"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "83540f837a8afc019423a8edb95b52a8effe46957ee402287f4292fae35be021"
+checksum = "46f71c0377baf4ef1cc3e3402ded576dccc315800fbc62dfc7fe04b009773b4a"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -60,6 +91,6 @@ dependencies = [
 
 [[package]]
 name = "unicode-ident"
-version = "1.0.12"
+version = "1.0.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"
+checksum = "adb9e6ca4f869e1180728b7950e35922a7fc6397f7b641499e8f3ef06e50dc83"
diff --git a/Cargo.toml b/Cargo.toml
index bfed38a..c480f21 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,15 +7,14 @@ license     = "GPL-3.0"
 name        = "language"
 readme      = "README.md"
 repository  = "https://github.com/hack-ink/language"
-version     = "0.1.2"
+version     = "0.1.3"
 
 [profile.ci-dev]
 incremental = false
 inherits    = "dev"
 
-# [profile.ci-release]
-# inherits = "release"
-# lto      = true
-
 [dependencies]
 serde = { version = "1.0", optional = true, features = ["derive"] }
+
+[dev-dependencies]
+serde_json = { version = "1.0" }
diff --git a/src/lib.rs b/src/lib.rs
index dbc47c0..1cc1aab 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,10 +9,11 @@ use serde::{
 	ser::Serializer,
 	Deserialize, Serialize,
 };
+#[cfg(all(not(feature = "serde"), test))] use serde_json as _;
 // self
 use Language::*;
 
-/// Language collection.
+#[allow(missing_docs)]
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub enum Language {
 	/// Afrikaans (South Africa)
@@ -1818,3 +1819,14 @@ impl<'de> Deserialize<'de> for Language {
 		Language::from_tag(&tag).ok_or_else(|| Error::unknown_variant(&tag, &[]))
 	}
 }
+
+#[cfg(feature = "serde")]
+#[test]
+fn serde_should_work() {
+	let lang = Language::EnUs;
+	let serialized = serde_json::to_string(&lang).unwrap();
+	assert_eq!(serialized, "\"en-US\"");
+
+	let deserialized: Language = serde_json::from_str(&serialized).unwrap();
+	assert_eq!(deserialized, lang);
+}