diff --git a/pkgs/by-name/pn/pngoptimizer/package.nix b/pkgs/by-name/pn/pngoptimizer/package.nix
index 8a0e510062a8..c1c4b6c70473 100644
--- a/pkgs/by-name/pn/pngoptimizer/package.nix
+++ b/pkgs/by-name/pn/pngoptimizer/package.nix
@@ -26,6 +26,9 @@ stdenv.mkDerivation (finalAttrs: {
     "DESTDIR=$(out)"
   ];
 
+  # Fix build with GCC 15
+  env.NIX_CFLAGS_COMPILE = "-Wno-error=old-style-definition";
+
   postInstall = ''
     mv $out/usr/bin $out/bin
     mv $out/usr/share $out/share