diff --git a/src/fenwicktree.rs b/src/fenwicktree.rs
index cfcf32a..5fedc13 100644
--- a/src/fenwicktree.rs
+++ b/src/fenwicktree.rs
@@ -1,6 +1,8 @@
+use std::fmt::{Debug, Error, Formatter};
 use std::ops::{Bound, RangeBounds};
 
 // Reference: https://en.wikipedia.org/wiki/Fenwick_tree
+#[derive(Clone)]
 pub struct FenwickTree<T> {
     n: usize,
     ary: Vec<T>,
@@ -55,6 +57,20 @@ impl<T: Clone + std::ops::AddAssign<T>> FenwickTree<T> {
     }
 }
 
+impl<T: Clone + Debug + std::ops::AddAssign<T>> Debug for FenwickTree<T> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
+        f.debug_struct("FenwickTree")
+            .field("n", &self.n)
+            .field(
+                "accum",
+                &(1..=self.n).map(|i| self.accum(i)).collect::<Vec<_>>(),
+            )
+            .field("e", &self.e)
+            .finish()?;
+        Ok(())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;