diff --git a/nixos/flake.lock b/nixos/flake.lock
index d24bc6c0..9ba11c30 100644
--- a/nixos/flake.lock
+++ b/nixos/flake.lock
@@ -1183,11 +1183,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1768349483,
-        "narHash": "sha256-dlWl/z/rdZmPGVexkYL1VLKBMU1e5Y1DZmQfiRf60cQ=",
+        "lastModified": 1768434960,
+        "narHash": "sha256-cJbFn17oyg6qAraLr+NVeNJrXsrzJdrudkzI4H2iTcg=",
         "owner": "nix-community",
         "repo": "home-manager",
-        "rev": "c5d67517bbcaf37e15c416219c965cc707a0ca24",
+        "rev": "b4d88c9ac42ae1a745283f6547701da43b6e9f9b",
         "type": "github"
       },
       "original": {
@@ -1318,11 +1318,11 @@
         "nixpkgs-regression": "nixpkgs-regression"
       },
       "locked": {
-        "lastModified": 1768309199,
-        "narHash": "sha256-8Pl9pVhr3AiPIHQU4P3jP0GRt5TGKeO2Kl2clszaXTg=",
+        "lastModified": 1768430150,
+        "narHash": "sha256-PPMZg7BV1oZeCA9zxh9QTeng3YJzXjyi3IQ4FwdRewc=",
         "owner": "NixOS",
         "repo": "nix",
-        "rev": "1b1c949d0cb4036bb210abdf222ede405588d898",
+        "rev": "f162bb62f773ca20553de361934fdd105d09b2d0",
         "type": "github"
       },
       "original": {
@@ -1372,11 +1372,11 @@
         "nixpkgs": "nixpkgs_8"
       },
       "locked": {
-        "lastModified": 1765841014,
-        "narHash": "sha256-55V0AJ36V5Egh4kMhWtDh117eE3GOjwq5LhwxDn9eHg=",
+        "lastModified": 1768404695,
+        "narHash": "sha256-eT3dNE2CQYcPDHaeRZAEFrZ0BmMq2wLxMp7hCmzOZBA=",
         "owner": "nix-community",
         "repo": "NixOS-WSL",
-        "rev": "be4af8042e7a61fa12fda58fe9a3b3babdefe17b",
+        "rev": "d0d3636b9d174c4558e3bbb18e194d970505fed8",
         "type": "github"
       },
       "original": {
@@ -1684,11 +1684,11 @@
     },
     "nixpkgs_9": {
       "locked": {
-        "lastModified": 1768127708,
-        "narHash": "sha256-1Sm77VfZh3mU0F5OqKABNLWxOuDeHIlcFjsXeeiPazs=",
+        "lastModified": 1768305791,
+        "narHash": "sha256-AIdl6WAn9aymeaH/NvBj0H9qM+XuAuYbGMZaP0zcXAQ=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "ffbc9f8cbaacfb331b6017d5a5abb21a492c9a38",
+        "rev": "1412caf7bf9e660f2f962917c14b1ea1c3bc695e",
         "type": "github"
       },
       "original": {
@@ -1756,11 +1756,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1768431631,
-        "narHash": "sha256-zxW0xlNUiAWCvCm+fC5BZxI0nP9hOV0HGTzsds0s1AQ=",
+        "lastModified": 1768454092,
+        "narHash": "sha256-rc8Zoa7tVQV+Q5vKkRL+2c0MZufxOnVNAOXFOaMYp7g=",
         "owner": "colonelpanic8",
         "repo": "org-agenda-api",
-        "rev": "26cd79e74aa10f3ae3ed482dda141bc297199589",
+        "rev": "89bca51fb105ccf2881611c7df1ef1a2b4b3de67",
         "type": "github"
       },
       "original": {
@@ -2300,11 +2300,11 @@
     },
     "unstable_3": {
       "locked": {
-        "lastModified": 1768127708,
-        "narHash": "sha256-1Sm77VfZh3mU0F5OqKABNLWxOuDeHIlcFjsXeeiPazs=",
+        "lastModified": 1768305791,
+        "narHash": "sha256-AIdl6WAn9aymeaH/NvBj0H9qM+XuAuYbGMZaP0zcXAQ=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "ffbc9f8cbaacfb331b6017d5a5abb21a492c9a38",
+        "rev": "1412caf7bf9e660f2f962917c14b1ea1c3bc695e",
         "type": "github"
       },
       "original": {
diff --git a/nixos/overlay.nix b/nixos/overlay.nix
index 476247f3..bd07b1e3 100644
--- a/nixos/overlay.nix
+++ b/nixos/overlay.nix
@@ -162,6 +162,13 @@ in
   in
   final.python3.withPackages my-python-packages;
 
+  # Fix synergy build with GCC 15 - missing #include <cstdint>
+  synergy = prev.synergy.overrideAttrs (oldAttrs: {
+    postPatch = (oldAttrs.postPatch or "") + ''
+      sed -i '/#include <cstring>/a #include <cstdint>' src/lib/server/InputFilter.cpp
+    '';
+  });
+
   pythonPackagesExtensions = prev.pythonPackagesExtensions ++ [
     (
       python-final: python-prev: {