diff --git a/pkgs/tools/text/patchutils/0.3.3.nix b/pkgs/tools/text/patchutils/0.3.3.nix
index f1aea0a847f0..2efd44fc787a 100644
--- a/pkgs/tools/text/patchutils/0.3.3.nix
+++ b/pkgs/tools/text/patchutils/0.3.3.nix
@@ -5,6 +5,10 @@ callPackage ./generic.nix (
   // {
     version = "0.3.3";
     sha256 = "0g5df00cj4nczrmr4k791l7la0sq2wnf8rn981fsrz1f3d2yix4i";
-    patches = [ ./drop-comments.patch ]; # we would get into a cycle when using fetchpatch on this one
+    patches = [
+      # we would get into a cycle when using fetchpatch on this one
+      ./drop-comments.patch
+      ./getenv-signature.patch
+    ];
   }
 )
diff --git a/pkgs/tools/text/patchutils/0.4.2.nix b/pkgs/tools/text/patchutils/0.4.2.nix
index 18625c2d9822..ef25f66d3876 100644
--- a/pkgs/tools/text/patchutils/0.4.2.nix
+++ b/pkgs/tools/text/patchutils/0.4.2.nix
@@ -7,6 +7,9 @@ callPackage ./generic.nix (
     sha256 = "sha256-iHWwll/jPeYriQ9s15O+f6/kGk5VLtv2QfH+1eu/Re0=";
     # for gitdiff
     extraBuildInputs = [ python3 ];
-    patches = [ ./Make-grepdiff1-test-case-pcre-aware.patch ];
+    patches = [
+      ./Make-grepdiff1-test-case-pcre-aware.patch
+      ./getenv-signature.patch
+    ];
   }
 )
diff --git a/pkgs/tools/text/patchutils/default.nix b/pkgs/tools/text/patchutils/default.nix
index c79b1d7110c7..04d033383c53 100644
--- a/pkgs/tools/text/patchutils/default.nix
+++ b/pkgs/tools/text/patchutils/default.nix
@@ -5,5 +5,8 @@ callPackage ./generic.nix (
   // {
     version = "0.3.4";
     sha256 = "0xp8mcfyi5nmb5a2zi5ibmyshxkb1zv1dgmnyn413m7ahgdx8mfg";
+    patches = [
+      ./getenv-signature.patch
+    ];
   }
 )
diff --git a/pkgs/tools/text/patchutils/getenv-signature.patch b/pkgs/tools/text/patchutils/getenv-signature.patch
new file mode 100644
index 000000000000..1a6956ca83cc
--- /dev/null
+++ b/pkgs/tools/text/patchutils/getenv-signature.patch
@@ -0,0 +1,46 @@
+From 64e5c63ef72ab97ecae6d43845634aa34da0b426 Mon Sep 17 00:00:00 2001
+From: Yureka <yuka@yuka.dev>
+Date: Sun, 11 Jan 2026 16:49:07 +0100
+Subject: [PATCH] getopt.{c,h}: Do not use unspecified signatures
+
+Unspecified signatures no longer work with C23, and the GNU getopt signature matches the one specified by POSIX
+---
+ src/getopt.c | 2 +-
+ src/getopt.h | 7 -------
+ 2 files changed, 1 insertion(+), 8 deletions(-)
+
+diff --git a/src/getopt.c b/src/getopt.c
+index 9bafa45..c268441 100644
+--- a/src/getopt.c
++++ b/src/getopt.c
+@@ -209,7 +209,7 @@ static char *posixly_correct;
+    whose names are inconsistent.  */
+ 
+ #ifndef getenv
+-extern char *getenv ();
++extern char *getenv (const char *);
+ #endif
+ 
+ static char *
+diff --git a/src/getopt.h b/src/getopt.h
+index a1b8dd6..0aea224 100644
+--- a/src/getopt.h
++++ b/src/getopt.h
+@@ -138,14 +138,7 @@ struct option
+    `getopt'.  */
+ 
+ #if (defined __STDC__ && __STDC__) || defined __cplusplus
+-# ifdef __GNU_LIBRARY__
+-/* Many other libraries have conflicting prototypes for getopt, with
+-   differences in the consts, in stdlib.h.  To avoid compilation
+-   errors, only prototype getopt for the GNU C library.  */
+ extern int getopt (int __argc, char *const *__argv, const char *__shortopts);
+-# else /* not __GNU_LIBRARY__ */
+-extern int getopt ();
+-# endif /* __GNU_LIBRARY__ */
+ 
+ # ifndef __need_getopt
+ extern int getopt_long (int __argc, char *const *__argv, const char *__shortopts,
+-- 
+2.52.0
+