diff --git a/pkgs/by-name/cr/creduce/fix-gcc15.patch b/pkgs/by-name/cr/creduce/fix-gcc15.patch
new file mode 100644
index 000000000000..42bd32aae05d
--- /dev/null
+++ b/pkgs/by-name/cr/creduce/fix-gcc15.patch
@@ -0,0 +1,53 @@
+From 1c715fef9113d5a5291694eab739d4a743ab08d5 Mon Sep 17 00:00:00 2001
+From: Bradley Walters <oss@walters.app>
+Date: Fri, 2 Jan 2026 22:02:30 -0800
+Subject: [PATCH] unifdef: constexpr is reserved in C23
+
+---
+ unifdef/unifdef.c | 10 +++++-----
+ 1 file changed, 5 insertions(+), 5 deletions(-)
+
+diff --git a/unifdef/unifdef.c b/unifdef/unifdef.c
+index 5c67cd44..692a1640 100644
+--- a/unifdef/unifdef.c
++++ b/unifdef/unifdef.c
+@@ -201,7 +201,7 @@ static int              depth;			/* current #if nesting */
+ static int              delcount;		/* count of deleted lines */
+ static unsigned         blankcount;		/* count of blank lines */
+ static unsigned         blankmax;		/* maximum recent blankcount */
+-static bool             constexpr;		/* constant #if expression */
++static bool             isconstexpr;		/* constant #if expression */
+ static bool             zerosyms;		/* to format symdepth output */
+ static bool             firstsym;		/* ditto */
+ 
+@@ -1078,7 +1078,7 @@ eval_unary(const struct ops *ops, long *valp, const char **cpp)
+ 			*valp = (value[sym] != NULL);
+ 			lt = *valp ? LT_TRUE : LT_FALSE;
+ 		}
+-		constexpr = false;
++		isconstexpr = false;
+ 	} else if (!endsym(*cp)) {
+ 		debug("eval%d symbol", prec(ops));
+ 		sym = findsym(&cp);
+@@ -1095,7 +1095,7 @@ eval_unary(const struct ops *ops, long *valp, const char **cpp)
+ 			lt = *valp ? LT_TRUE : LT_FALSE;
+ 			cp = skipargs(cp);
+ 		}
+-		constexpr = false;
++		isconstexpr = false;
+ 	} else {
+ 		debug("eval%d bad expr", prec(ops));
+ 		return (LT_ERROR);
+@@ -1162,10 +1162,10 @@ ifeval(const char **cpp)
+ 	long val = 0;
+ 
+ 	debug("eval %s", *cpp);
+-	constexpr = killconsts ? false : true;
++	isconstexpr = killconsts ? false : true;
+ 	ret = eval_table(eval_ops, &val, cpp);
+ 	debug("eval = %d", val);
+-	return (constexpr ? LT_IF : ret == LT_ERROR ? LT_IF : ret);
++	return (isconstexpr ? LT_IF : ret == LT_ERROR ? LT_IF : ret);
+ }
+ 
+ /*
diff --git a/pkgs/development/tools/misc/creduce/default.nix b/pkgs/by-name/cr/creduce/package.nix
similarity index 89%
rename from pkgs/development/tools/misc/creduce/default.nix
rename to pkgs/by-name/cr/creduce/package.nix
index 23d88f07cdcb..03f135937da5 100644
--- a/pkgs/development/tools/misc/creduce/default.nix
+++ b/pkgs/by-name/cr/creduce/package.nix
@@ -4,13 +4,15 @@
   fetchFromGitHub,
   cmake,
   makeWrapper,
-  llvm,
-  libclang,
+  llvmPackages_18,
   flex,
   zlib,
   perlPackages,
   util-linux,
 }:
+let
+  llvmPackages = llvmPackages_18;
+in
 
 stdenv.mkDerivation {
   pname = "creduce";
@@ -23,6 +25,11 @@ stdenv.mkDerivation {
     hash = "sha256-RbxFqZegsCxnUaIIA5OfTzx1wflCPeF+enQt90VwMgA=";
   };
 
+  patches = [
+    # https://github.com/csmith-project/creduce/pull/290
+    ./fix-gcc15.patch
+  ];
+
   postPatch = ''
     substituteInPlace {clex,clang_delta,delta,unifdef,creduce,.}/CMakeLists.txt --replace-fail \
     "cmake_minimum_required(VERSION 2.8.12)" "cmake_minimum_required(VERSION 3.10)"
@@ -39,14 +46,14 @@ stdenv.mkDerivation {
   nativeBuildInputs = [
     cmake
     makeWrapper
-    llvm.dev
+    llvmPackages.llvm.dev
   ];
   buildInputs = [
     # Ensure stdenv's CC is on PATH before clang-unwrapped
     stdenv.cc
     # Actual deps:
-    llvm
-    libclang
+    llvmPackages.llvm
+    llvmPackages.libclang
     flex
     zlib
   ]
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 2fd1b75e67c3..8f1d8a0ce349 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -5538,10 +5538,6 @@ with pkgs;
 
   credstash = with python3Packages; toPythonApplication credstash;
 
-  creduce = callPackage ../development/tools/misc/creduce {
-    inherit (llvmPackages_18) llvm libclang;
-  };
-
   css-html-js-minify = with python3Packages; toPythonApplication css-html-js-minify;
 
   cvise = python3Packages.callPackage ../development/tools/misc/cvise {