diff --git a/src/collections/sparse_set.rs b/src/collections/sparse_set.rs
index 5e0ec84..d808acb 100644
--- a/src/collections/sparse_set.rs
+++ b/src/collections/sparse_set.rs
@@ -30,6 +30,19 @@ impl<T> SparseSet<T> {
     }
 }
 
+impl<T, PackedAlloc, SparseAlloc> core::fmt::Debug for SparseSet<T, PackedAlloc, SparseAlloc>
+where
+    T: core::fmt::Debug,
+    PackedAlloc: Allocator,
+    SparseAlloc: Allocator,
+{
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_map()
+            .entries(self.dense_to_id.iter().zip(self.dense.iter()))
+            .finish()
+    }
+}
+
 impl<T, PackedAlloc, SparseAlloc> SparseSet<T, PackedAlloc, SparseAlloc>
 where
     PackedAlloc: Allocator,
@@ -236,7 +249,10 @@ mod tests {
 
         assert_eq!(sparse_set.remove(SPARSE_PAGESIZE + 2).unwrap(), 3);
         assert_eq!(sparse_set.sparse[1].as_ref().unwrap().1, 2);
-        assert_eq!(sparse_set.keys(), [10, 11, 12, SPARSE_PAGESIZE, SPARSE_PAGESIZE + 1]);
+        assert_eq!(
+            sparse_set.keys(),
+            [10, 11, 12, SPARSE_PAGESIZE, SPARSE_PAGESIZE + 1]
+        );
         assert_eq!(sparse_set.values(), [1, 2, 2, 1, 2]);
 
         assert_eq!(sparse_set.remove(SPARSE_PAGESIZE + 1).unwrap(), 2);
@@ -249,25 +265,44 @@ mod tests {
         assert_eq!(sparse_set.keys(), [10, 11, 12]);
         assert_eq!(sparse_set.values(), [1, 2, 2]);
 
-
         sparse_set.insert(SPARSE_PAGESIZE, 1);
         sparse_set.insert(SPARSE_PAGESIZE + 1, 2);
         sparse_set.insert(SPARSE_PAGESIZE + 2, 3);
 
         assert_eq!(sparse_set.remove(10).unwrap(), 1);
         assert_eq!(sparse_set.sparse[0].as_ref().unwrap().1, 2);
-        // swap-remove 
-        assert_eq!(sparse_set.keys(), [SPARSE_PAGESIZE + 2, 11, 12, SPARSE_PAGESIZE, SPARSE_PAGESIZE + 1]);
+        // swap-remove
+        assert_eq!(
+            sparse_set.keys(),
+            [
+                SPARSE_PAGESIZE + 2,
+                11,
+                12,
+                SPARSE_PAGESIZE,
+                SPARSE_PAGESIZE + 1
+            ]
+        );
         assert_eq!(sparse_set.values(), [3, 2, 2, 1, 2]);
 
         assert_eq!(sparse_set.remove(11).unwrap(), 2);
         assert_eq!(sparse_set.sparse[0].as_ref().unwrap().1, 1);
-        assert_eq!(sparse_set.keys(), [SPARSE_PAGESIZE + 2, SPARSE_PAGESIZE + 1, 12, SPARSE_PAGESIZE]);
+        assert_eq!(
+            sparse_set.keys(),
+            [
+                SPARSE_PAGESIZE + 2,
+                SPARSE_PAGESIZE + 1,
+                12,
+                SPARSE_PAGESIZE
+            ]
+        );
         assert_eq!(sparse_set.values(), [3, 2, 2, 1]);
 
         assert_eq!(sparse_set.remove(12).unwrap(), 2);
         assert!(sparse_set.sparse[0].is_none());
-        assert_eq!(sparse_set.keys(), [SPARSE_PAGESIZE + 2, SPARSE_PAGESIZE + 1, SPARSE_PAGESIZE]);
+        assert_eq!(
+            sparse_set.keys(),
+            [SPARSE_PAGESIZE + 2, SPARSE_PAGESIZE + 1, SPARSE_PAGESIZE]
+        );
         assert_eq!(sparse_set.values(), [3, 2, 1]);
     }
 }