diff --git a/pkgs/by-name/sy/synergy/include_cstdint.patch b/pkgs/by-name/sy/synergy/include_cstdint.patch
new file mode 100644
index 000000000000..e597751c1b3a
--- /dev/null
+++ b/pkgs/by-name/sy/synergy/include_cstdint.patch
@@ -0,0 +1,12 @@
+diff --git a/src/lib/server/InputFilter.cpp b/src/lib/server/InputFilter.cpp
+index da29f5b..65c500f 100755
+--- a/src/lib/server/InputFilter.cpp
++++ b/src/lib/server/InputFilter.cpp
+@@ -26,6 +26,7 @@
+
+ #include <cstdlib>
+ #include <cstring>
++#include <cstdint>
+
+ // -----------------------------------------------------------------------------
+ // Input Filter Condition Classes
diff --git a/pkgs/by-name/sy/synergy/package.nix b/pkgs/by-name/sy/synergy/package.nix
index 37e95f1340e1..4d7917d4f9f3 100644
--- a/pkgs/by-name/sy/synergy/package.nix
+++ b/pkgs/by-name/sy/synergy/package.nix
@@ -42,6 +42,10 @@ stdenv.mkDerivation (finalAttrs: {
   patches = [
     # Without this OpenSSL from nixpkgs is not detected
     ./darwin-non-static-openssl.patch
+
+    # This missing include broke the build on GCC 15
+    # This can be removed once we switch to a newer version
+    ./include_cstdint.patch
   ];
 
   postPatch = ''