diff --git a/pkgs/os-specific/darwin/sigtool/0001-fix-build-with-gcc.patch b/pkgs/os-specific/darwin/sigtool/0001-fix-build-with-gcc.patch
new file mode 100644
index 000000000000..dfebbdfb566e
--- /dev/null
+++ b/pkgs/os-specific/darwin/sigtool/0001-fix-build-with-gcc.patch
@@ -0,0 +1,24 @@
+From b18ae56b1bee86808d40f89900f999e835a7e1e9 Mon Sep 17 00:00:00 2001
+From: Randy Eckenrode <randy@largeandhighquality.com>
+Date: Fri, 13 Feb 2026 19:05:02 -0500
+Subject: [PATCH] fix-build-with-gcc
+
+---
+ emit.h | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/emit.h b/emit.h
+index 340f314..a8a6d3b 100644
+--- a/emit.h
++++ b/emit.h
+@@ -6,6 +6,7 @@
+ #include <memory>
+ #include <arpa/inet.h>
+ #include <cmath>
++#include <cstdint>
+ 
+ namespace SigTool {
+ 
+-- 
+2.51.2
+
diff --git a/pkgs/os-specific/darwin/sigtool/default.nix b/pkgs/os-specific/darwin/sigtool/default.nix
index 226956ba1cdd..d565bd4fb8c8 100644
--- a/pkgs/os-specific/darwin/sigtool/default.nix
+++ b/pkgs/os-specific/darwin/sigtool/default.nix
@@ -17,6 +17,11 @@ stdenv.mkDerivation rec {
     sha256 = "sha256-K3VSFaqcZEomF7kROJz+AwxdW1MmxxEFDaRnWnzcw54=";
   };
 
+  patches = [
+    # Fix missing `UINT64_C` when building with GCC on Linux
+    ./0001-fix-build-with-gcc.patch
+  ];
+
   nativeBuildInputs = [ pkg-config ];
   buildInputs = [ openssl ];