diff --git a/flake.nix b/flake.nix
index 0ef79e1d0..c8c42a742 100644
--- a/flake.nix
+++ b/flake.nix
@@ -129,6 +129,7 @@
           ./nix/ext/pg_hashids.nix
           ./nix/ext/pgsodium.nix
           ./nix/ext/pg_graphql.nix
+          ./nix/ext/pg_mooncake.nix
           ./nix/ext/pg_stat_monitor.nix
           ./nix/ext/pg_jsonschema.nix
           ./nix/ext/pgvector.nix
diff --git a/nix/ext/pg_mooncake.nix b/nix/ext/pg_mooncake.nix
new file mode 100644
index 000000000..f6b1347de
--- /dev/null
+++ b/nix/ext/pg_mooncake.nix
@@ -0,0 +1,88 @@
+{
+  lib,
+  stdenv,
+  fetchFromGitHub,
+  postgresql,
+  cmake,
+  openssl,
+  curl,
+  pkg-config,
+  cacert,
+  rust-bin,
+}:
+
+let
+  rustVersion = "1.81.0";
+  targets = [
+    "aarch64-apple-darwin"
+    "x86_64-apple-darwin"
+    "x86_64-unknown-linux-gnu"
+    "aarch64-unknown-linux-gnu"
+  ];
+  rustc = rust-bin.stable."${rustVersion}".default.override {
+    inherit targets;
+  };
+  cargo = rust-bin.stable."${rustVersion}".default.override {
+    inherit targets;
+  };
+in
+stdenv.mkDerivation rec {
+  pname = "pg_mooncake";
+  version = "61a2c495ba8e8bbcf59142f05dc85a3059bdf42c";
+
+  src = fetchFromGitHub {
+    owner = "olirice";
+    repo  = pname;
+    rev   = version;
+    hash  = "sha256-zyQ0LREOSIF+25NODoZb8fTVH0sYEVu5YUqsJigWEb8=";
+    fetchSubmodules = true;
+  };
+
+  # Tools needed for building:
+  nativeBuildInputs = [
+    cargo
+    rustc
+    cmake
+    pkg-config
+  ];
+
+  buildInputs = [
+    postgresql
+    openssl
+    curl
+    cacert
+  ];
+
+  # Skip the default configure phase because there's no top-level CMakeLists.txt.
+  dontConfigure = true;
+
+  # Use "make release -j" with Nix's parallel build cores:
+  buildPhase = ''
+    export SSL_CERT_FILE=${cacert}/etc/ssl/certs/ca-bundle.crt
+
+    # Make sure these env vars are set in the same shell invocation:
+    export HOME=$PWD/home
+    export CARGO_HOME=$HOME/cargo
+    mkdir -p "$CARGO_HOME"
+
+    # Pass HOME and CARGO_HOME explicitly to `make`, in case the upstream
+    # Makefile does something like `HOME ?= /homeless-shelter`.
+    HOME="$HOME" \
+    CARGO_HOME="$CARGO_HOME" \
+      make release -j$NIX_BUILD_CORES PG_CONFIG="${postgresql}/bin/pg_config"
+  '';
+
+  installPhase = ''
+    mkdir -p $out/{lib,share/postgresql/extension}
+
+    cp *${postgresql.dlSuffix}      $out/lib
+    cp *.sql     $out/share/postgresql/extension
+  '';
+
+  meta = with lib; {
+    description = "Mooncake: user-defined pipeline analytics in Postgres";
+    homepage    = "https://github.com/Mooncake-Labs/${pname}";
+    platforms   = postgresql.meta.platforms;
+    license     = licenses.postgresql;
+  };
+}