diff --git a/src/db/dir.rs b/src/db/dir.rs
index 43d6448..4dae2cf 100644
--- a/src/db/dir.rs
+++ b/src/db/dir.rs
@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::collections::HashSet;
 use std::fmt::{self, Display, Formatter};
 
 use serde::{Deserialize, Serialize};
@@ -12,7 +13,7 @@ pub struct DirV4<'a> {
     pub rank: Rank,
     pub last_accessed: Epoch,
     #[serde(borrow)]
-    pub aliases: Vec<Cow<'a, str>>,
+    pub aliases: HashSet<Cow<'a, str>>,
 }
 
 #[derive(Clone, Debug, Deserialize, Serialize)]
@@ -26,7 +27,7 @@ pub struct DirV3<'a> {
 pub trait Dir {
     fn path(&self) -> &str;
     fn score(&self, now: Epoch) -> Rank;
-    fn aliases(&self) -> &[Cow<'_, str>];
+    fn aliases(&self) -> Option<&HashSet<Cow<'_, str>>>;
 }
 
 impl Dir for DirV4<'_> {
@@ -48,8 +49,8 @@ impl Dir for DirV4<'_> {
         }
     }
 
-    fn aliases(&self) -> &[Cow<'_, str>] {
-        &self.aliases
+    fn aliases(&self) -> Option<&HashSet<Cow<'_, str>>> {
+        Some(&self.aliases)
     }
 }
 
@@ -78,8 +79,8 @@ impl Dir for DirV3<'_> {
         }
     }
 
-    fn aliases(&self) -> &[Cow<'_, str>] {
-        return &[];
+    fn aliases(&self) -> Option<&HashSet<Cow<'_, str>>> {
+        None
     }
 }
 
@@ -118,8 +119,10 @@ impl<'a, T: Dir> Display for DirDisplay<'a, T> {
             write!(f, "{score:>6.1}{}", self.separator)?;
         }
 
-        if self.aliases {
-            for alias in self.dir.aliases() {
+        if self.aliases
+            && let Some(aliases) = self.dir.aliases()
+        {
+            for alias in aliases {
                 write!(f, "{} ", alias)?;
             }
             write!(f, "{}", self.separator)?;
diff --git a/src/db/mod.rs b/src/db/mod.rs
index dab0cf0..046297c 100644
--- a/src/db/mod.rs
+++ b/src/db/mod.rs
@@ -1,6 +1,7 @@
 mod dir;
 mod stream;
 
+use std::collections::HashSet;
 use std::path::{Path, PathBuf};
 use std::{fs, io};
 
@@ -78,12 +79,15 @@ impl Database {
             Some(dir) => {
                 dir.rank = (dir.rank + by).max(0.0);
                 if let Some(al) = alias {
-                    dir.aliases.push(al.into().into());
+                    dir.aliases.insert(al.into().into());
                 }
             }
             None => {
-                let aliases =
-                    if let Some(alias) = alias { vec![alias.into().into()] } else { Vec::new() };
+                let aliases = if let Some(alias) = alias {
+                    HashSet::from([alias.into().into()])
+                } else {
+                    HashSet::new()
+                };
                 dirs.push(DirV4 {
                     path: path.into().into(),
                     rank: by.max(0.0),
@@ -107,8 +111,11 @@ impl Database {
         alias: Option<impl AsRef<str> + Into<String>>,
     ) {
         self.with_dirs_mut(|dirs| {
-            let aliases =
-                if let Some(alias) = alias { vec![alias.into().into()] } else { Vec::new() };
+            let aliases = if let Some(alias) = alias {
+                HashSet::from([alias.into().into()])
+            } else {
+                HashSet::new()
+            };
             dirs.push(DirV4 { path: path.into().into(), rank, last_accessed: now, aliases })
         });
         self.with_dirty_mut(|dirty| *dirty = true);
@@ -128,12 +135,15 @@ impl Database {
                 dir.rank = (dir.rank + by).max(0.0);
                 dir.last_accessed = now;
                 if let Some(al) = alias {
-                    dir.aliases.push(al.into().into());
+                    dir.aliases.insert(al.into().into());
                 }
             }
             None => {
-                let aliases =
-                    if let Some(alias) = alias { vec![alias.into().into()] } else { Vec::new() };
+                let aliases = if let Some(alias) = alias {
+                    HashSet::from([alias.into().into()])
+                } else {
+                    HashSet::new()
+                };
                 dirs.push(DirV4 {
                     path: path.into().into(),
                     rank: by.max(0.0),
@@ -278,7 +288,7 @@ impl Database {
                         path: dir.path,
                         rank: dir.rank,
                         last_accessed: dir.last_accessed,
-                        aliases: Vec::new(),
+                        aliases: HashSet::new(),
                     })
                     .collect()
             }
diff --git a/src/db/stream.rs b/src/db/stream.rs
index 62d2efc..aa9251c 100644
--- a/src/db/stream.rs
+++ b/src/db/stream.rs
@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::collections::HashSet;
 use std::iter::Rev;
 use std::ops::Range;
 use std::path::Path;
@@ -109,10 +110,10 @@ impl<'a> Stream<'a> {
         true
     }
 
-    fn match_aliases(&self, aliases: &[Cow<'a, str>]) -> bool {
+    fn match_aliases(&self, aliases: &HashSet<Cow<'a, str>>) -> bool {
         for keyword in self.options.keywords.iter().rev() {
             // Alias matching is intended to be case-sensitive
-            if aliases.iter().any(|a| a == keyword.as_str()) {
+            if aliases.contains(keyword.as_str()) {
                 return true;
             }
         }
diff --git a/src/import/atuin.rs b/src/import/atuin.rs
index 7596013..310e850 100644
--- a/src/import/atuin.rs
+++ b/src/import/atuin.rs
@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::collections::HashSet;
 use std::io::{BufRead, BufReader};
 use std::process::{Child, ChildStdout, Command, Stdio};
 use std::str;
@@ -64,7 +65,7 @@ impl Iter {
             path: Cow::Owned(path.to_string()),
             rank: 1.0,
             last_accessed: timestamp as Epoch,
-            aliases: Vec::new(),
+            aliases: HashSet::new(),
         };
         Ok(dir)
     }
diff --git a/src/import/autojump.rs b/src/import/autojump.rs
index 06ba392..df59fb9 100644
--- a/src/import/autojump.rs
+++ b/src/import/autojump.rs
@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::collections::HashSet;
 use std::fs::File;
 use std::io::{BufRead, BufReader};
 use std::path::PathBuf;
@@ -56,7 +57,7 @@ impl<R: BufRead> Iter<R> {
             path: Cow::Owned(path.to_string()),
             rank,
             last_accessed: 0,
-            aliases: Vec::new(),
+            aliases: HashSet::new(),
         })
     }
 }
diff --git a/src/import/z.rs b/src/import/z.rs
index d43bcaf..43e51c5 100644
--- a/src/import/z.rs
+++ b/src/import/z.rs
@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::collections::HashSet;
 use std::fs::File;
 use std::io::{BufRead, BufReader};
 use std::path::PathBuf;
@@ -54,7 +55,12 @@ impl<R: BufRead> Iter<R> {
 
         let path = split.next().ok_or_else(err)?;
 
-        Ok(DirV4 { path: Cow::Owned(path.to_string()), rank, last_accessed, aliases: Vec::new() })
+        Ok(DirV4 {
+            path: Cow::Owned(path.to_string()),
+            rank,
+            last_accessed,
+            aliases: HashSet::new(),
+        })
     }
 }