diff --git a/ofborg/src/nix.rs b/ofborg/src/nix.rs
index d0339ce..a231e0a 100644
--- a/ofborg/src/nix.rs
+++ b/ofborg/src/nix.rs
@@ -6,6 +6,7 @@ use std::fs::File;
 use std::io::Seek;
 use std::io::SeekFrom;
 
+#[derive(Clone, Debug, PartialEq)]
 pub struct Nix {
     system: String,
     remote: String
@@ -19,35 +20,46 @@ pub fn new(system: String, remote: String) -> Nix {
 }
 
 impl Nix {
-    pub fn safely_build_attrs(&self, nixpkgs: &Path, attrs: Vec<String>) -> Result<File,File> {
-        let mut nixpath = OsString::new();
-        nixpath.push("nixpkgs=");
-        nixpath.push(nixpkgs.as_os_str());
+    pub fn with_system(&self, system: String) -> Nix {
+        return Nix{
+            system: system,
+            remote: self.remote.clone(),
+        };
+    }
 
-        let mut attrargs: Vec<String> = Vec::with_capacity(attrs.len() * 2);
+    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));
+        attrargs.push(String::from("--no-out-link"));
+        attrargs.push(String::from("--keep-going"));
         for attr in attrs {
             attrargs.push(String::from("-A"));
             attrargs.push(attr);
         }
 
+        return self.safely("nix-build", nixpkgs, attrargs);
+    }
+
+    pub fn safely(&self, cmd: &str, nixpkgs: &Path, args: Vec<String>) -> Result<File,File> {
+        let mut nixpath = OsString::new();
+        nixpath.push("nixpkgs=");
+        nixpath.push(nixpkgs.as_os_str());
+
         let stdout = tempfile().expect("Fetching a stdout tempfile");
         let stderr = stdout.try_clone().expect("Cloning stdout for stderr");
         let mut reader = stderr.try_clone().expect("Cloning stderr to the reader");
 
-        let status = Command::new("nix-build")
+        let status = Command::new(cmd)
             .env_clear()
             .current_dir(nixpkgs)
             .stdout(Stdio::from(stdout))
             .stderr(Stdio::from(stderr))
             .env("NIX_PATH", nixpath)
             .env("NIX_REMOTE", &self.remote)
-            .arg("--no-out-link")
             .args(&["--option", "restrict-eval", "true"])
             .args(&["--argstr", "system", &self.system])
-            .arg("--keep-going")
-            .args(attrargs)
+            .args(args)
             .status()
-            .expect("Running nix-build");
+            .expect(format!("Running {:?}", cmd).as_ref());
 
         reader.seek(SeekFrom::Start(0)).expect("Seeking to Start(0)");