diff --git a/flake.nix b/flake.nix
index 6be157d..50af1b7 100644
--- a/flake.nix
+++ b/flake.nix
@@ -37,7 +37,7 @@ rust-project TODO: write shell script for automatically updating `cargoHash`
       rustSettings = with pkgs; {
         src = ./.;
         nativeBuildInputs = [ pkg-config ];
-        buildInputs = [ openssl hddtemp ];
+        buildInputs = [ openssl hddtemp msmtp ];
         cargoHash = nixpkgs.lib.fakeHash;
       };
       meta = with nixpkgs.lib; {