diff --git a/book/book.toml b/book/book.toml
index 27c2d8a..1a65a73 100644
--- a/book/book.toml
+++ b/book/book.toml
@@ -4,3 +4,6 @@ language = "en"
 multilingual = false
 src = "src"
 title = "augurs - a time series toolkit"
+
+[rust]
+edition = "2021"
diff --git a/book/src/tutorials/clustering.md b/book/src/tutorials/clustering.md
index 6d01e5e..17a6816 100644
--- a/book/src/tutorials/clustering.md
+++ b/book/src/tutorials/clustering.md
@@ -14,7 +14,10 @@ Let's start with a simple example using DBSCAN clustering:
 
 ```rust
 # extern crate augurs;
-use augurs::{clustering::DbscanClusterer, dtw::Dtw};
+use augurs::{
+    clustering::{DbscanCluster, DbscanClusterer},
+    dtw::Dtw,
+};
 
 // Sample time series data
 const SERIES: &[&[f64]] = &[
@@ -39,11 +42,20 @@ fn main() {
     let min_cluster_size = 2;
 
     // Perform clustering
-    let clusters: Vec<isize> = DbscanClusterer::new(epsilon, min_cluster_size)
+    let clusters = DbscanClusterer::new(epsilon, min_cluster_size)
         .fit(&distance_matrix);
 
     // Clusters are labeled: -1 for noise, 0+ for cluster membership
-    assert_eq!(clusters, vec![0, 0, 1, 1, -1]);
+    assert_eq!(
+        clusters,
+        vec![
+            DbscanCluster::Cluster(1.try_into().unwrap()),
+            DbscanCluster::Cluster(1.try_into().unwrap()),
+            DbscanCluster::Cluster(2.try_into().unwrap()),
+            DbscanCluster::Cluster(2.try_into().unwrap()),
+            DbscanCluster::Noise,
+        ]
+    );
 }
 ```
 
diff --git a/crates/augurs-clustering/README.md b/crates/augurs-clustering/README.md
index d6658e2..f7b47dd 100644
--- a/crates/augurs-clustering/README.md
+++ b/crates/augurs-clustering/README.md
@@ -8,7 +8,7 @@ A crate such as [`augurs-dtw`] must be used to calculate the distance matrix for
 ## Usage
 
 ```rust
-use augurs::clustering::{DbscanClusterer, DistanceMatrix};
+use augurs::clustering::{DbscanCluster, DbscanClusterer, DistanceMatrix};
 
 # fn main() -> Result<(), Box<dyn std::error::Error>> {
 // Start with a distance matrix.
@@ -32,7 +32,16 @@ let min_cluster_size = 2;
 // Use DBSCAN to detect clusters of series.
 // Note that we don't need to specify the number of clusters in advance.
 let clusters = DbscanClusterer::new(epsilon, min_cluster_size).fit(&distance_matrix);
-assert_eq!(clusters, vec![0, 0, 0, 1, 1]);
+assert_eq!(
+    clusters,
+    vec![
+        DbscanCluster::Cluster(1.try_into().unwrap()),
+        DbscanCluster::Cluster(1.try_into().unwrap()),
+        DbscanCluster::Cluster(1.try_into().unwrap()),
+        DbscanCluster::Cluster(2.try_into().unwrap()),
+        DbscanCluster::Cluster(2.try_into().unwrap()),
+    ],
+);
 # Ok(())
 # }
 ```
diff --git a/crates/augurs-clustering/src/lib.rs b/crates/augurs-clustering/src/lib.rs
index b52b905..8a02a15 100644
--- a/crates/augurs-clustering/src/lib.rs
+++ b/crates/augurs-clustering/src/lib.rs
@@ -1,9 +1,64 @@
 #![doc = include_str!("../README.md")]
 
-use std::collections::VecDeque;
+use std::{collections::VecDeque, num::NonZeroU32};
 
 pub use augurs_core::DistanceMatrix;
 
+/// A cluster identified by the DBSCAN algorithm.
+///
+/// This is either a noise cluster, or a cluster with a specific ID.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum DbscanCluster {
+    /// A noise cluster.
+    Noise,
+    /// A cluster with the given ID.
+    ///
+    /// The ID is not guaranteed to remain the same between runs of the algorithm.
+    ///
+    /// We use a `NonZeroU32` here to ensure that the ID is never zero. This is mostly
+    /// just a size optimization.
+    Cluster(NonZeroU32),
+}
+
+impl DbscanCluster {
+    /// Returns true if this cluster is a noise cluster.
+    pub fn is_noise(&self) -> bool {
+        matches!(self, Self::Noise)
+    }
+
+    /// Returns true if this cluster is a cluster with the given ID.
+    pub fn is_cluster(&self) -> bool {
+        matches!(self, Self::Cluster(_))
+    }
+
+    /// Returns the ID of the cluster, if it is a cluster, or `-1` if it is a noise cluster.
+    pub fn as_i32(&self) -> i32 {
+        match self {
+            Self::Noise => -1,
+            Self::Cluster(id) => id.get() as i32,
+        }
+    }
+
+    fn increment(&mut self) {
+        match self {
+            Self::Noise => unreachable!(),
+            Self::Cluster(id) => *id = id.checked_add(1).expect("cluster ID overflow"),
+        }
+    }
+}
+
+// Simplify tests by allowing comparisons with i32.
+#[cfg(test)]
+impl PartialEq<i32> for DbscanCluster {
+    fn eq(&self, other: &i32) -> bool {
+        if self.is_noise() {
+            *other == -1
+        } else {
+            self.as_i32() == *other
+        }
+    }
+}
+
 /// DBSCAN clustering algorithm.
 #[derive(Debug)]
 pub struct DbscanClusterer {
@@ -40,11 +95,11 @@ impl DbscanClusterer {
 
     /// Run the DBSCAN clustering algorithm.
     ///
-    /// The return value is a vector of cluster assignments, with `-1` indicating noise.
-    pub fn fit(&self, distance_matrix: &DistanceMatrix) -> Vec<isize> {
+    /// The return value is a vector of cluster assignments, with `DbscanCluster::Noise` indicating noise.
+    pub fn fit(&self, distance_matrix: &DistanceMatrix) -> Vec<DbscanCluster> {
         let n = distance_matrix.shape().0;
-        let mut clusters = vec![-1; n];
-        let mut cluster = 0;
+        let mut clusters = vec![DbscanCluster::Noise; n];
+        let mut cluster = DbscanCluster::Cluster(NonZeroU32::new(1).unwrap());
         let mut visited = vec![false; n];
         let mut to_visit = VecDeque::with_capacity(n);
 
@@ -53,7 +108,7 @@ impl DbscanClusterer {
 
         for (i, d) in distance_matrix.iter().enumerate() {
             // Skip if already assigned to a cluster.
-            if clusters[i] != -1 {
+            if clusters[i].is_cluster() {
                 continue;
             }
             self.find_neighbours(i, d, &mut neighbours);
@@ -67,7 +122,7 @@ impl DbscanClusterer {
             clusters[i] = cluster;
             // Mark all noise neighbours as visited and add them to the queue.
             for neighbour in neighbours.drain(..) {
-                if clusters[neighbour] == -1 {
+                if clusters[neighbour].is_noise() {
                     visited[neighbour] = true;
                     to_visit.push_back(neighbour);
                 }
@@ -87,7 +142,7 @@ impl DbscanClusterer {
                     }
                 }
             }
-            cluster += 1;
+            cluster.increment();
         }
         clusters
     }
@@ -123,19 +178,19 @@ mod test {
         assert_eq!(clusters, vec![-1, -1, -1, -1]);
 
         let clusters = DbscanClusterer::new(1.0, 2).fit(&distance_matrix);
-        assert_eq!(clusters, vec![0, 0, -1, -1]);
+        assert_eq!(clusters, vec![1, 1, -1, -1]);
 
         let clusters = DbscanClusterer::new(1.0, 3).fit(&distance_matrix);
         assert_eq!(clusters, vec![-1, -1, -1, -1]);
 
         let clusters = DbscanClusterer::new(2.0, 2).fit(&distance_matrix);
-        assert_eq!(clusters, vec![0, 0, 0, -1]);
+        assert_eq!(clusters, vec![1, 1, 1, -1]);
 
         let clusters = DbscanClusterer::new(2.0, 3).fit(&distance_matrix);
-        assert_eq!(clusters, vec![0, 0, 0, -1]);
+        assert_eq!(clusters, vec![1, 1, 1, -1]);
 
         let clusters = DbscanClusterer::new(3.0, 3).fit(&distance_matrix);
-        assert_eq!(clusters, vec![0, 0, 0, 0]);
+        assert_eq!(clusters, vec![1, 1, 1, 1]);
     }
 
     #[test]
@@ -151,36 +206,36 @@ mod test {
         let distance_matrix = DistanceMatrix::try_from_square(distance_matrix).unwrap();
         let clusters = DbscanClusterer::new(10.0, 3).fit(&distance_matrix);
         let expected = vec![
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 2, -1, 2, -1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 3, -1, 3, -1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
         ];
         assert_eq!(clusters, expected);
     }
diff --git a/crates/augurs/tests/integration.rs b/crates/augurs/tests/integration.rs
index 068132a..a8d992c 100644
--- a/crates/augurs/tests/integration.rs
+++ b/crates/augurs/tests/integration.rs
@@ -18,6 +18,9 @@ fn test_changepoint() {
 #[cfg(feature = "clustering")]
 #[test]
 fn test_clustering() {
+    fn convert_clusters(clusters: Vec<augurs_clustering::DbscanCluster>) -> Vec<i32> {
+        clusters.into_iter().map(|c| c.as_i32()).collect()
+    }
     use augurs::{clustering::DbscanClusterer, DistanceMatrix};
     let distance_matrix = vec![
         vec![0.0, 1.0, 2.0, 3.0],
@@ -27,22 +30,22 @@ fn test_clustering() {
     ];
     let distance_matrix = DistanceMatrix::try_from_square(distance_matrix).unwrap();
     let clusters = DbscanClusterer::new(0.5, 2).fit(&distance_matrix);
-    assert_eq!(clusters, vec![-1, -1, -1, -1]);
+    assert_eq!(convert_clusters(clusters), vec![-1, -1, -1, -1]);
 
     let clusters = DbscanClusterer::new(1.0, 2).fit(&distance_matrix);
-    assert_eq!(clusters, vec![0, 0, -1, -1]);
+    assert_eq!(convert_clusters(clusters), vec![1, 1, -1, -1]);
 
     let clusters = DbscanClusterer::new(1.0, 3).fit(&distance_matrix);
-    assert_eq!(clusters, vec![-1, -1, -1, -1]);
+    assert_eq!(convert_clusters(clusters), vec![-1, -1, -1, -1]);
 
     let clusters = DbscanClusterer::new(2.0, 2).fit(&distance_matrix);
-    assert_eq!(clusters, vec![0, 0, 0, -1]);
+    assert_eq!(convert_clusters(clusters), vec![1, 1, 1, -1]);
 
     let clusters = DbscanClusterer::new(2.0, 3).fit(&distance_matrix);
-    assert_eq!(clusters, vec![0, 0, 0, -1]);
+    assert_eq!(convert_clusters(clusters), vec![1, 1, 1, -1]);
 
     let clusters = DbscanClusterer::new(3.0, 3).fit(&distance_matrix);
-    assert_eq!(clusters, vec![0, 0, 0, 0]);
+    assert_eq!(convert_clusters(clusters), vec![1, 1, 1, 1]);
 }
 
 #[cfg(feature = "dtw")]
diff --git a/crates/pyaugurs/src/clustering.rs b/crates/pyaugurs/src/clustering.rs
index adad947..b96086a 100644
--- a/crates/pyaugurs/src/clustering.rs
+++ b/crates/pyaugurs/src/clustering.rs
@@ -82,8 +82,15 @@ impl Dbscan {
         &self,
         py: Python<'_>,
         distance_matrix: InputDistanceMatrix<'_>,
-    ) -> PyResult<Py<PyArray1<isize>>> {
+    ) -> PyResult<Py<PyArray1<i32>>> {
         let distance_matrix = distance_matrix.try_into()?;
-        Ok(self.inner.fit(&distance_matrix).into_pyarray(py).into())
+        Ok(self
+            .inner
+            .fit(&distance_matrix)
+            .into_iter()
+            .map(|x| x.as_i32())
+            .collect::<Vec<_>>()
+            .into_pyarray(py)
+            .into())
     }
 }
diff --git a/examples/clustering/examples/dbscan_clustering.rs b/examples/clustering/examples/dbscan_clustering.rs
index 08fab21..fb93b1e 100644
--- a/examples/clustering/examples/dbscan_clustering.rs
+++ b/examples/clustering/examples/dbscan_clustering.rs
@@ -7,7 +7,10 @@
 //! The resulting clusters are assigned a label of -1 for noise, 0 for the first cluster, and 1 for
 //! the second cluster.
 
-use augurs::{clustering::DbscanClusterer, dtw::Dtw};
+use augurs::{
+    clustering::{DbscanCluster, DbscanClusterer},
+    dtw::Dtw,
+};
 
 // This is a very trivial example dataset containing 5 time series which
 // form two obvious clusters, plus a noise cluster.
@@ -49,7 +52,16 @@ fn main() {
     let min_cluster_size = 2;
 
     // Run DBSCAN clustering on the distance matrix.
-    let clusters: Vec<isize> =
-        DbscanClusterer::new(epsilon, min_cluster_size).fit(&distance_matrix);
-    assert_eq!(clusters, vec![0, 0, 1, 1, -1]);
+    let clusters = DbscanClusterer::new(epsilon, min_cluster_size).fit(&distance_matrix);
+    println!("Clusters: {:?}", clusters);
+    assert_eq!(
+        clusters,
+        vec![
+            DbscanCluster::Cluster(1.try_into().unwrap()),
+            DbscanCluster::Cluster(1.try_into().unwrap()),
+            DbscanCluster::Cluster(2.try_into().unwrap()),
+            DbscanCluster::Cluster(2.try_into().unwrap()),
+            DbscanCluster::Noise,
+        ]
+    );
 }
diff --git a/js/augurs-clustering-js/src/lib.rs b/js/augurs-clustering-js/src/lib.rs
index a3c8a69..350af65 100644
--- a/js/augurs-clustering-js/src/lib.rs
+++ b/js/augurs-clustering-js/src/lib.rs
@@ -44,7 +44,12 @@ impl DbscanClusterer {
     /// The return value is an `Int32Array` of cluster IDs, with `-1` indicating noise.
     #[wasm_bindgen]
     #[allow(non_snake_case)]
-    pub fn fit(&self, distanceMatrix: VecVecF64) -> Result<Vec<isize>, JsError> {
-        Ok(self.inner.fit(&DistanceMatrix::new(distanceMatrix)?.into()))
+    pub fn fit(&self, distanceMatrix: VecVecF64) -> Result<Vec<i32>, JsError> {
+        Ok(self
+            .inner
+            .fit(&DistanceMatrix::new(distanceMatrix)?.into())
+            .into_iter()
+            .map(|x| x.as_i32())
+            .collect::<Vec<_>>())
     }
 }
diff --git a/js/testpkg/clustering.test.ts b/js/testpkg/clustering.test.ts
index 66ed7d3..8ed45c2 100644
--- a/js/testpkg/clustering.test.ts
+++ b/js/testpkg/clustering.test.ts
@@ -22,7 +22,7 @@ describe('clustering', () => {
       [2, 3, 0, 4],
       [3, 3, 4, 0],
     ]);
-    expect(labels).toEqual(new Int32Array([0, 0, -1, -1]));
+    expect(labels).toEqual(new Int32Array([1, 1, -1, -1]));
   });
 
   it('can be fit with a raw distance matrix of typed arrays', () => {
@@ -33,7 +33,7 @@ describe('clustering', () => {
       new Float64Array([2, 3, 0, 4]),
       new Float64Array([3, 3, 4, 0]),
     ]);
-    expect(labels).toEqual(new Int32Array([0, 0, -1, -1]));
+    expect(labels).toEqual(new Int32Array([1, 1, -1, -1]));
   });
 
   it('can be fit with a distance matrix from augurs', () => {
@@ -46,6 +46,6 @@ describe('clustering', () => {
     ]);
     const clusterer = new DbscanClusterer({ epsilon: 0.5, minClusterSize: 2 });
     const labels = clusterer.fit(distanceMatrix);
-    expect(labels).toEqual(new Int32Array([0, 0, 0, -1]));
+    expect(labels).toEqual(new Int32Array([1, 1, 1, -1]));
   })
 });