diff --git a/src/deploy.rs b/src/deploy.rs
index fa235e2..03561d3 100644
--- a/src/deploy.rs
+++ b/src/deploy.rs
@@ -1,10 +1,13 @@
-use color_eyre::{eyre::Result, owo_colors::OwoColorize};
+use color_eyre::{
+    eyre::{Context, Result},
+    owo_colors::OwoColorize,
+};
 use futures::future::join_all;
 use openssh::{KnownHosts, Session};
 use std::{
     env,
     path::PathBuf,
-    process::{Command, Stdio},
+    process::{Command, Output, Stdio},
 };
 
 fn gen_systems_path(system: &str) -> String {
@@ -14,10 +17,7 @@ fn gen_systems_path(system: &str) -> String {
     )
 }
 
-pub fn build(systems: &[String], show_trace: bool) -> Result<()> {
-    if systems.is_empty() {
-        return Ok(());
-    }
+pub fn build(systems: &[String], show_trace: bool) -> Result<Output> {
     let dir = env::var("PRJ_ROOT")
         .map(PathBuf::from)
         .or_else(|_| env::current_dir())?;
@@ -50,8 +50,7 @@ pub fn build(systems: &[String], show_trace: bool) -> Result<()> {
         .arg("--print-out-paths")
         .arg("--no-link")
         .args(configs);
-    cmd.spawn()?.wait()?;
-    Ok(())
+    cmd.output().wrap_err("Error building systems")
 }
 
 pub async fn deploy(systems: &[String], show_trace: bool, mode: &str) -> Result<()> {
@@ -68,22 +67,24 @@ pub async fn deploy(systems: &[String], show_trace: bool, mode: &str) -> Result<
         .await
         .into_iter()
         .collect::<std::result::Result<Vec<_>, openssh::Error>>()?;
-    build(
-        &systems.iter().map(|x| x.to_string()).collect::<Vec<_>>(),
-        show_trace,
+    let toplevels = String::from_utf8(
+        build(
+            &systems.iter().map(|x| x.to_string()).collect::<Vec<_>>(),
+            show_trace,
+        )?
+        .stdout,
     )?;
-    for (system, (con, host)) in systems.into_iter().zip(connections.into_iter().zip(hosts)) {
-        let path = gen_systems_path(system);
-        let mut cmd = Command::new("nix");
-        let cmd = cmd.arg("eval").arg("--read-only").arg("--raw").arg(path);
-        let toplevel = String::from_utf8(cmd.output()?.stdout)?;
+    for (toplevel, (system, (con, host))) in toplevels
+        .lines()
+        .zip(systems.into_iter().zip(connections.into_iter().zip(hosts)))
+    {
         println!("Copyings toplevel for {}", system.blue());
         let mut cmd = Command::new("nix");
         let cmd = cmd
             .arg("copy")
             .arg("--to")
             .arg(format!("ssh://{}", host))
-            .arg(&toplevel);
+            .arg(toplevel);
         cmd.spawn()?.wait()?;
         let prev_system = con
             .command("readlink")
@@ -97,7 +98,7 @@ pub async fn deploy(systems: &[String], show_trace: bool, mode: &str) -> Result<
             .arg("--profile")
             .arg("/nix/var/nix/profiles/system")
             .arg("--set")
-            .arg(&toplevel)
+            .arg(toplevel)
             .spawn()
             .await?;
         con.command(format!("{}/bin/switch-to-configuration", toplevel))