diff --git a/pkgs/by-name/fo/foomatic-filters/fix-incompatible-pointer-types.patch b/pkgs/by-name/fo/foomatic-filters/fix-incompatible-pointer-types.patch
new file mode 100644
index 000000000000..04c181c6d5ad
--- /dev/null
+++ b/pkgs/by-name/fo/foomatic-filters/fix-incompatible-pointer-types.patch
@@ -0,0 +1,25 @@
+From 822bf358b1e47704365feb84cac8a0af08611ea5 Mon Sep 17 00:00:00 2001
+From: Moraxyc <i@qaq.li>
+Date: Thu, 1 Jan 2026 20:28:52 +0800
+Subject: [PATCH] fix incompatible pointer types
+
+---
+ process.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/process.h b/process.h
+index b95dcb4..58aa8bf 100644
+--- a/process.h
++++ b/process.h
+@@ -28,7 +28,7 @@
+ #include <sys/types.h>
+ #include <sys/wait.h>
+ 
+-pid_t start_process(const char *name, int (*proc_func)(), void *user_arg, FILE **fdin, FILE **fdout);
++pid_t start_process(const char *name, int (*proc_func)(FILE *, FILE *, void *), void *user_arg, FILE **fdin, FILE **fdout);
+ pid_t start_system_process(const char *name, const char *command, FILE **fdin, FILE **fdout);
+ 
+ /* returns command's return status (see waitpid(2)) */
+-- 
+2.51.2
+
diff --git a/pkgs/by-name/fo/foomatic-filters/package.nix b/pkgs/by-name/fo/foomatic-filters/package.nix
index 5f69ec334aa2..0ba0eb13fa3c 100644
--- a/pkgs/by-name/fo/foomatic-filters/package.nix
+++ b/pkgs/by-name/fo/foomatic-filters/package.nix
@@ -33,6 +33,9 @@ stdenv.mkDerivation rec {
       url = "https://salsa.debian.org/debian/foomatic-filters/raw/a3abbef2d2f8c7e62d2fe64f64afe294563fdf8f/debian/patches/0500-r7406_also_consider_the_back_tick_as_an_illegal_shell_escape_character.patch";
       sha256 = "055nwi3sjf578nk40bqsch3wx8m2h65hdih0wmxflb6l0hwkq4p4";
     })
+    # Fix build with gcc15
+    #   process.h:31:45: note: expected 'int (*)(void)' but argument is of type 'int (*)(FILE *, FILE *, void *)'
+    ./fix-incompatible-pointer-types.patch
   ];
 
   preConfigure = ''