diff --git a/kakplugin/src/errors.rs b/kakplugin/src/errors.rs
index accbf11..5d4295d 100644
--- a/kakplugin/src/errors.rs
+++ b/kakplugin/src/errors.rs
@@ -1,4 +1,4 @@
-use std::num::ParseIntError;
+use std::{fmt, fmt::Display, num::ParseIntError};
 
 #[derive(Debug)]
 pub enum KakError {
@@ -16,10 +16,14 @@ pub enum KakError {
     NotImplemented(&'static str),
     /// Custom error string
     Custom(String),
+    /// Custom static error string
+    CustomStatic(&'static str),
     /// The selections/selections_desc list passed was empty
     SetEmptySelections,
 }
 
+impl std::error::Error for KakError {}
+
 impl KakError {
     pub fn details(&self) -> String {
         match self {
@@ -30,6 +34,7 @@ impl KakError {
             Self::Io(e) => format!("{e:?}"),
             Self::NotImplemented(e) => e.to_string(),
             Self::Custom(s) => s.clone(),
+            Self::CustomStatic(s) => s.to_string(),
             Self::SetEmptySelections => {
                 String::from("Attempted to set selections/selections_desc to empty list")
             }
@@ -37,22 +42,23 @@ impl KakError {
     }
 }
 
-impl ToString for KakError {
-    fn to_string(&self) -> String {
-        format!(
-            "Error: {}",
-            match self {
-                Self::EnvVarNotSet(_) => "env var not set",
-                Self::EnvVarUnicode(_) => "env var not unicode",
-                Self::Parse(_) => "Could not parse",
-                Self::KakResponse(_) => "Invalid kak response",
-                Self::Io(_) => "IO error",
-                Self::NotImplemented(_) => "Not Implemented",
-                Self::Custom(s) => s,
-                Self::SetEmptySelections =>
-                    "Attempted to set selections/selections_desc to empty list",
-            }
-        )
+impl Display for KakError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Error: ")?;
+        match self {
+            Self::EnvVarNotSet(_) => write!(f, "env var not set"),
+            Self::EnvVarUnicode(_) => write!(f, "env var not unicode"),
+            Self::Parse(_) => write!(f, "Could not parse"),
+            Self::KakResponse(_) => write!(f, "Invalid kak response"),
+            Self::Io(_) => write!(f, "IO error"),
+            Self::NotImplemented(_) => write!(f, "Not Implemented"),
+            Self::Custom(s) => write!(f, "{}", s),
+            Self::CustomStatic(s) => write!(f, "{}", s),
+            Self::SetEmptySelections => write!(
+                f,
+                "Attempted to set selections/selections_desc to empty list"
+            ),
+        }
     }
 }
 
diff --git a/kakplugin/src/types.rs b/kakplugin/src/types.rs
index fd58ad4..b433bb5 100644
--- a/kakplugin/src/types.rs
+++ b/kakplugin/src/types.rs
@@ -325,7 +325,7 @@ impl FromStr for AnchorPosition {
     }
 }
 
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
 pub enum Register {
     Numeric0,
     Numeric1,
diff --git a/src/incr.rs b/src/incr.rs
index 96abcc7..6215927 100644
--- a/src/incr.rs
+++ b/src/incr.rs
@@ -40,11 +40,12 @@ pub fn incr(options: &Options, should_increment: bool) -> Result<String, KakErro
         )
     } else {
         format!(
-            "{} {} selections by {} ({} errors)",
+            "{} {} selections by {} ({} error{})",
             if should_increment { "Incr" } else { "Decr" },
             selections.len().saturating_sub(err_count),
             options.amount,
             err_count,
+            if err_count == 1 { "" } else { "s" }
         )
     })
 }
diff --git a/src/main.rs b/src/main.rs
index 38953c6..d84003a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -9,6 +9,7 @@
 #![allow(dead_code, unused_imports)]
 #![feature(slice_group_by)]
 #![feature(slice_take)]
+#![feature(array_chunks)]
 
 mod box_;
 mod errors;
@@ -22,6 +23,7 @@ mod stdin;
 mod trim;
 mod uniq;
 mod utils;
+mod xlookup;
 // mod xargs;
 use clap::{Parser, Subcommand};
 use kakplugin::{display_message, get_var, KakError};
@@ -63,7 +65,11 @@ enum Commands {
     Stdin(stdin::Options),
     #[clap(about = "Make boxes out of selections", visible_aliases = &["square"])]
     Box_(box_::Options),
+    #[clap(about = "Map selections based on a register", visible_aliases = &["vlookup"])]
+    Xlookup(xlookup::Options),
+    #[clap(about = "Increment selections")]
     Decr(incr::Options),
+    #[clap(about = "Decrement selections")]
     Incr(incr::Options),
 }
 
@@ -114,6 +120,7 @@ fn run() -> Result<String, KakError> {
         // Commands::Xargs(o) => xargs::xargs(o),
         Commands::Stdin(o) => stdin::stdin(o),
         Commands::Box_(o) => box_::box_(o),
+        Commands::Xlookup(o) => xlookup::xlookup(o),
         Commands::Incr(o) => incr::incr(o, true),
         Commands::Decr(o) => incr::incr(o, false),
     }
diff --git a/src/math_eval.rs b/src/math_eval.rs
index 8d82000..5beb041 100644
--- a/src/math_eval.rs
+++ b/src/math_eval.rs
@@ -25,9 +25,10 @@ pub fn math_eval(_options: &Options) -> Result<String, KakError> {
         format!("Processed {} selections", selections.len())
     } else {
         format!(
-            "Processed {} selections ({} errors)",
+            "Processed {} selections ({} error{})",
             selections.len().saturating_sub(err_count),
-            err_count
+            err_count,
+            if err_count == 1 { "" } else { "s" }
         )
     })
 }
diff --git a/src/xlookup.rs b/src/xlookup.rs
new file mode 100644
index 0000000..2d2daf9
--- /dev/null
+++ b/src/xlookup.rs
@@ -0,0 +1,75 @@
+use crate::utils::get_hash;
+use evalexpr::{eval, Value};
+use kakplugin::{
+    get_selections, open_command_fifo, set_selections, types::Register, KakError, Selection,
+};
+use std::{
+    collections::{
+        btree_map::Entry::{Occupied, Vacant},
+        hash_map::DefaultHasher,
+        BTreeMap,
+    },
+    hash::{Hash, Hasher},
+    io::Write,
+};
+
+#[derive(clap::StructOpt, Debug)]
+pub struct Options {
+    #[clap(help = "Register with the lookup table")]
+    register: Register,
+}
+pub fn xlookup(options: &Options) -> Result<String, KakError> {
+    let lookup_table = build_lookuptable(options.register)?;
+    eprintln!("Lookup table: {lookup_table:#?}");
+
+    let selections = get_selections(None)?;
+
+    let mut err_count: usize = 0;
+
+    set_selections(selections.iter().map(|key| {
+        match lookup_table.get(&get_hash(&key, false, None, false)) {
+            Some(v) => v.to_string(),
+            None => {
+                eprintln!(
+                    "Nothing for '{key}' ({})",
+                    get_hash(&key, false, None, false)
+                );
+                err_count += 1;
+                String::from("")
+            }
+        }
+    }))?;
+
+    Ok(if err_count == 0 {
+        format!("Xlookup {} selections", selections.len())
+    } else {
+        format!(
+            "Xlookup {} selections ({} error{})",
+            selections.len().saturating_sub(err_count),
+            err_count,
+            if err_count == 1 { "" } else { "s" }
+        )
+    })
+}
+
+pub fn build_lookuptable(reg: Register) -> Result<BTreeMap<u64, Selection>, KakError> {
+    let mut selections = get_selections(Some(&format!("\"{reg}z")))?;
+    let mut iter = selections.array_chunks_mut();
+    let ret = iter.try_fold(BTreeMap::new(), |mut acc, [key, value]| {
+        match acc.entry(get_hash(&key, false, None, false)) {
+            Occupied(_) => Err(KakError::Custom(format!("Duplicate key '{key}'"))),
+            Vacant(v) => {
+                v.insert(value.to_owned());
+                Ok(acc)
+            }
+        }
+    })?;
+
+    if !iter.into_remainder().is_empty() {
+        Err(KakError::CustomStatic("Odd number of selections"))
+    } else if ret.is_empty() {
+        Err(KakError::CustomStatic("No selections"))
+    } else {
+        Ok(ret)
+    }
+}