diff --git a/src/lib.rs b/src/lib.rs
index 1b13932..796174d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -80,15 +80,14 @@ impl fmt::Debug for Orientation {
 
 #[derive(Debug, Default)]
 pub struct Screen {
-    pub name: Option<String>,
-    pub connection: String,
+    pub name: String,
     pub resolution: Resolution,
     pub offset: Offset,
     pub orientation: Orientation,
 }
 
-impl fmt::Display for Screen {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+impl Screen {
+    fn metamode(&self, map: &ScreenMapping) -> Result<String, CommandError> {
         let Resolution { width, height } = self.resolution;
         let Offset { x, y } = self.offset;
         let (in_w, in_h) = match self.orientation {
@@ -102,8 +101,13 @@ impl fmt::Display for Screen {
             Orientation::Left => "90",
         };
 
-        write!(f, "{connection}: {w}x{h} @{in_w}x{in_h} +{x}+{y} {{ViewPortIn={in_w}x{in_h}, ViewPortOut={w}x{h}+0+0, Rotation={rotation}}}",
-               connection=self.connection,
+        let connection = match map.get(&self.name) {
+            Some(connection) => connection,
+            None => return Err(CommandError::MissingMonitor(self.name.to_string())),
+        };
+
+        Ok(format!("{connection}: {w}x{h} @{in_w}x{in_h} +{x}+{y} {{ViewPortIn={in_w}x{in_h}, ViewPortOut={w}x{h}+0+0, Rotation={rotation}}}",
+               connection=connection,
                w=width,
                h=height,
                in_w=in_w,
@@ -111,7 +115,7 @@ impl fmt::Display for Screen {
                x=x,
                y=y,
                rotation=rotation,
-               )
+               ))
     }
 }
 
@@ -120,7 +124,7 @@ pub struct Config {
     pub screens: Vec<Screen>,
 }
 
-pub fn run_cmd(screen_mapping: ScreenMapping, cfg: Config) -> Result<Output, CommandError> {
+pub fn run_cmd(screen_mapping: &ScreenMapping, cfg: Config) -> Result<Output, CommandError> {
     let args = build_cmd_args(screen_mapping, cfg)?;
     if cfg!(debug_assertions) {
         Ok(Command::new("echo").args(args).output()?)
@@ -129,12 +133,15 @@ pub fn run_cmd(screen_mapping: ScreenMapping, cfg: Config) -> Result<Output, Com
     }
 }
 
-fn build_cmd_args(screen_mapping: ScreenMapping, cfg: Config) -> Result<Vec<String>, CommandError> {
+fn build_cmd_args(
+    screen_mapping: &ScreenMapping,
+    cfg: Config,
+) -> Result<Vec<String>, CommandError> {
     let metamode = cfg
         .screens
         .iter()
-        .map(|c| c.to_string())
-        .collect::<Vec<String>>()
+        .map(|c| c.metamode(screen_mapping))
+        .collect::<Result<Vec<String>, CommandError>>()?
         .join(", ");
     Ok(vec![
         "nvidia-settings",
@@ -155,8 +162,7 @@ mod tests {
         let cfg = Config {
             screens: vec![
                 Screen {
-                    name: Some("DELL U2415".to_string()),
-                    connection: "DFP-5.8".to_string(),
+                    name: "DELL U2415".to_string(),
                     resolution: Resolution {
                         width: 1920,
                         height: 1200,
@@ -165,8 +171,7 @@ mod tests {
                     ..Default::default()
                 },
                 Screen {
-                    name: Some("LG Electronics 34UM95".to_string()),
-                    connection: "DFP-0.1".to_string(),
+                    name: "LG Electronics 34UM95".to_string(),
                     resolution: Resolution {
                         width: 3440,
                         height: 1440,
@@ -175,8 +180,7 @@ mod tests {
                     ..Default::default()
                 },
                 Screen {
-                    name: Some("Lenovo Group Limited P27h-20".to_string()),
-                    connection: "DFP-0.8".to_string(),
+                    name: "Lenovo Group Limited P27h-20".to_string(),
                     resolution: Resolution {
                         width: 2560,
                         height: 1440,
@@ -195,7 +199,7 @@ mod tests {
         .map(|(k, v)| (k.to_string(), v.to_string()))
         .collect();
         assert_eq!(
-            build_cmd_args(map, cfg).expect("failed build_cmd_args"),
+            build_cmd_args(&map, cfg).expect("failed build_cmd_args"),
             vec![
                 "nvidia-settings",
                 "--assign",
diff --git a/src/main.rs b/src/main.rs
index dc2d370..4c106b6 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -6,8 +6,7 @@ fn main() -> Result<()> {
     let cfg = Config {
         screens: vec![
             Screen {
-                name: Some("DELL U2415".to_string()),
-                connection: "DFP-5.8".to_string(),
+                name: ("DELL U2415".to_string()),
                 resolution: Resolution {
                     width: 1920,
                     height: 1200,
@@ -16,8 +15,7 @@ fn main() -> Result<()> {
                 ..Default::default()
             },
             Screen {
-                name: Some("LG Electronics 34UM95".to_string()),
-                connection: "DFP-0.1".to_string(),
+                name: ("LG Electronics 34UM95".to_string()),
                 resolution: Resolution {
                     width: 3440,
                     height: 1440,
@@ -26,8 +24,7 @@ fn main() -> Result<()> {
                 ..Default::default()
             },
             Screen {
-                name: Some("Lenovo Group Limited P27h-20".to_string()),
-                connection: "DFP-0.8".to_string(),
+                name: ("Lenovo Group Limited P27h-20".to_string()),
                 resolution: Resolution {
                     width: 2560,
                     height: 1440,
@@ -39,7 +36,7 @@ fn main() -> Result<()> {
     };
 
     let map = screen_mapping_from_xorg_log("/var/log/Xorg.0.log")?;
-    let cmd = run_cmd(map, cfg)?;
+    let cmd = run_cmd(&map, cfg)?;
     println!("cmd {:#?}", cmd);
 
     Ok(())