diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5a3914a..b200cf3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ## [Unreleased]
 
+### Added
+
+- Add `php84` dev shell.
+
 ### Changed
 
 - Refactor to use [devshell](https://flake.parts/options/devshell.html).
diff --git a/modules/php84.nix b/modules/php84.nix
new file mode 100644
index 0000000..e4d5919
--- /dev/null
+++ b/modules/php84.nix
@@ -0,0 +1,18 @@
+{ commonPhpPackages, ... }:
+
+{
+  perSystem =
+    { pkgs, ... }:
+    {
+      devShells.php84 = pkgs.mkShell {
+        packages = with pkgs; [
+          php84
+          php84Packages.composer
+        ] ++ commonPhpPackages pkgs;
+
+        shellHook = ''
+          php --version
+        '';
+      };
+    };
+}