diff --git a/flake.nix b/flake.nix
index 93f9fd2..52691bc 100644
--- a/flake.nix
+++ b/flake.nix
@@ -57,6 +57,12 @@
             export = false;
           };
           packages.default = pkgs.callPackage ./default.nix {};
+          # the C api for embedding, as lib/libhydrant_ffi.a and include/hydrant.h
+          packages.ffi = config.packages.default.overrideAttrs {
+            pname = "hydrant-ffi";
+            cargoBuildFlags = [ "-p" "hydrant-ffi" ];
+            postInstall = "install -Dm644 ffi/include/hydrant.h -t $out/include";
+          };
           apps.build-docs = { type = "app"; program = "${buildDocs}/bin/build-docs"; };
           apps.deploy-docs = { type = "app"; program = "${deployDocs}/bin/deploy-docs"; };
           devShells.default = config.nci.outputs."hydrant".devShell.overrideAttrs (old: {