diff --git a/nix/backend.nix b/nix/backend.nix
index c4e0fe2..c2a3697 100644
--- a/nix/backend.nix
+++ b/nix/backend.nix
@@ -8,7 +8,15 @@ rustPlatform.buildRustPackage rec {
   pname = "backend";
   version = "0.1";
 
-  src = ../.;
+  src = lib.fileset.toSource {
+    root = ../.;
+    fileset = lib.fileset.unions [
+      ../Cargo.lock
+      ../Cargo.toml
+      ../crates
+      ../.cargo
+    ];
+  };
 
   cargoLock = {
     lockFile = ../Cargo.lock;