diff --git a/rand_distr/src/weighted_tree.rs b/rand_distr/src/weighted_tree.rs
index 6883967981..5eb82d3f45 100644
--- a/rand_distr/src/weighted_tree.rs
+++ b/rand_distr/src/weighted_tree.rs
@@ -88,11 +88,15 @@ use serde::{Deserialize, Serialize};
     serde(bound(deserialize = "W: Deserialize<'de>, W::Sampler: Deserialize<'de>"))
 )]
 #[derive(Clone, Default, Debug, PartialEq)]
-pub struct WeightedTreeIndex<W: SampleUniform> {
+pub struct WeightedTreeIndex<
+    W: Clone + PartialEq + PartialOrd + SampleUniform + SubAssign<W> + Weight,
+> {
     subtotals: Vec<W>,
 }
 
-impl<W: Clone + PartialEq + PartialOrd + SampleUniform + Weight> WeightedTreeIndex<W> {
+impl<W: Clone + PartialEq + PartialOrd + SampleUniform + SubAssign<W> + Weight>
+    WeightedTreeIndex<W>
+{
     /// Creates a new [`WeightedTreeIndex`] from a slice of weights.
     pub fn new<I>(weights: I) -> Result<Self, WeightedError>
     where
@@ -138,28 +142,22 @@ impl<W: Clone + PartialEq + PartialOrd + SampleUniform + Weight> WeightedTreeInd
     }
 
     /// Gets the weight at an index.
-    pub fn get(&self, index: usize) -> W
-    where
-        W: for<'a> SubAssign<&'a W>,
-    {
+    pub fn get(&self, index: usize) -> W {
         let left_index = 2 * index + 1;
         let right_index = 2 * index + 2;
         let mut w = self.subtotals[index].clone();
-        w -= &self.subtotal(left_index);
-        w -= &self.subtotal(right_index);
+        w -= self.subtotal(left_index);
+        w -= self.subtotal(right_index);
         w
     }
 
     /// Removes the last weight and returns it, or [`None`] if it is empty.
-    pub fn pop(&mut self) -> Option<W>
-    where
-        W: for<'a> SubAssign<&'a W>,
-    {
+    pub fn pop(&mut self) -> Option<W> {
         self.subtotals.pop().map(|weight| {
             let mut index = self.len();
             while index != 0 {
                 index = (index - 1) / 2;
-                self.subtotals[index] -= &weight;
+                self.subtotals[index] -= weight.clone();
             }
             weight
         })
@@ -186,15 +184,12 @@ impl<W: Clone + PartialEq + PartialOrd + SampleUniform + Weight> WeightedTreeInd
     }
 
     /// Updates the weight at an index.
-    pub fn update(&mut self, mut index: usize, weight: W) -> Result<(), WeightedError>
-    where
-        W: for<'a> SubAssign<&'a W>,
-    {
+    pub fn update(&mut self, mut index: usize, weight: W) -> Result<(), WeightedError> {
         if weight < W::ZERO {
             return Err(WeightedError::InvalidWeight);
         }
         let mut difference = weight;
-        difference -= &self.get(index);
+        difference -= self.get(index);
         if difference == W::ZERO {
             return Ok(());
         }