diff --git a/nixos/doc/manual/release-notes/rl-2505.section.md b/nixos/doc/manual/release-notes/rl-2505.section.md
index 013a1a8ba1da..31b57c914b91 100644
--- a/nixos/doc/manual/release-notes/rl-2505.section.md
+++ b/nixos/doc/manual/release-notes/rl-2505.section.md
@@ -23,7 +23,7 @@
   NEWS can been viewed from Emacs by typing `C-h n`, or by clicking `Help->Emacs News` from the menu bar.
   It can also be browsed [online](https://git.savannah.gnu.org/cgit/emacs.git/tree/etc/NEWS?h=emacs-30).
 
-- The default PHP version has been updated to 8.3.
+- The default PHP version has been updated to 8.4.
 
 - The default Erlang OTP version has been updated to 27.
 
diff --git a/nixos/modules/services/web-apps/selfoss.nix b/nixos/modules/services/web-apps/selfoss.nix
index 81701f2cc001..47ca75f00794 100644
--- a/nixos/modules/services/web-apps/selfoss.nix
+++ b/nixos/modules/services/web-apps/selfoss.nix
@@ -158,7 +158,7 @@ in
 
     systemd.services.selfoss-update = {
       serviceConfig = {
-        ExecStart = "${pkgs.php}/bin/php ${dataDir}/cliupdate.php";
+        ExecStart = "${pkgs.php83}/bin/php ${dataDir}/cliupdate.php";
         User = "${cfg.user}";
       };
       startAt = "hourly";
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 7282526af683..f73f6c698230 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -6862,7 +6862,7 @@ with pkgs;
   # PHP interpreters, packages and extensions.
   #
   # Set default PHP interpreter, extensions and packages
-  php = php83;
+  php = php84;
   phpExtensions = php.extensions;
   phpPackages = php.packages;