diff --git a/ofborg/src/nix.rs b/ofborg/src/nix.rs
index dff5818..d8be6c8 100644
--- a/ofborg/src/nix.rs
+++ b/ofborg/src/nix.rs
@@ -27,8 +27,9 @@ impl Nix {
         };
     }
 
-    pub fn safely_build_attrs(&self, nixpkgs: &Path, attrs: Vec<String>) -> Result<File,File> {
-        let mut attrargs: Vec<String> = Vec::with_capacity(2 + (attrs.len() * 2));
+    pub fn safely_build_attrs(&self, nixpkgs: &Path, file: &str, attrs: Vec<String>) -> Result<File,File> {
+        let mut attrargs: Vec<String> = Vec::with_capacity(3 + (attrs.len() * 2));
+        attrargs.push(file.to_owned());
         attrargs.push(String::from("--no-out-link"));
         attrargs.push(String::from("--keep-going"));
         for attr in attrs {
diff --git a/ofborg/src/tasks/build.rs b/ofborg/src/tasks/build.rs
index ee629fe..954ce4f 100644
--- a/ofborg/src/tasks/build.rs
+++ b/ofborg/src/tasks/build.rs
@@ -80,7 +80,9 @@ impl worker::SimpleWorker for BuildWorker {
 
         let success: bool;
         let reader: BufReader<File>;
-        match self.nix.safely_build_attrs(refpath.as_ref(), job.attrs.clone()) {
+        match self.nix.safely_build_attrs(refpath.as_ref(),
+                                          "./default.nix",
+                                          job.attrs.clone()) {
             Ok(r) => {
                 success = true;
                 reader = BufReader::new(r);