diff --git a/pkgs/by-name/d-/d-seams/cxxopts-cstdint.patch b/pkgs/by-name/d-/d-seams/cxxopts-cstdint.patch
new file mode 100644
index 000000000000..0ffb08bfab16
--- /dev/null
+++ b/pkgs/by-name/d-/d-seams/cxxopts-cstdint.patch
@@ -0,0 +1,11 @@
+diff --git a/src/include/external/cxxopts.hpp b/src/include/external/cxxopts.hpp
+--- a/src/include/external/cxxopts.hpp
++++ b/src/include/external/cxxopts.hpp
+@@ -26,6 +26,7 @@ THE SOFTWARE.
+ #define CXXOPTS_HPP_INCLUDED
+
+ #include <cctype>
++#include <cstdint>
+ #include <cstring>
+ #include <exception>
+ #include <iostream>
diff --git a/pkgs/by-name/d-/d-seams/package.nix b/pkgs/by-name/d-/d-seams/package.nix
index fdb927462723..7c325f0571f2 100644
--- a/pkgs/by-name/d-/d-seams/package.nix
+++ b/pkgs/by-name/d-/d-seams/package.nix
@@ -36,6 +36,8 @@ clangStdenv.mkDerivation rec {
       url = "https://github.com/d-SEAMS/seams-core/commit/f6156057e43d0aa1a0df9de67d8859da9c30302d.patch";
       hash = "sha256-PLbT1lqdw+69lIHH96MPcGRjfIeZyb88vc875QLYyqw=";
     })
+    # Add missing <cstdint> include for uint8_t in vendored cxxopts.
+    ./cxxopts-cstdint.patch
   ];
   postPatch = ''
     substituteInPlace CMakeLists.txt \