diff --git a/src/dynamics/joint/impulse_joint/impulse_joint_set.rs b/src/dynamics/joint/impulse_joint/impulse_joint_set.rs
index 093a372..716ad61 100644
--- a/src/dynamics/joint/impulse_joint/impulse_joint_set.rs
+++ b/src/dynamics/joint/impulse_joint/impulse_joint_set.rs
@@ -1,4 +1,4 @@
-use parry::utils::hashmap::HashMap;
+use parry::utils::hashset::HashSet;
 
 use super::ImpulseJoint;
 use crate::geometry::{InteractionGraph, RigidBodyGraphIndex, TemporaryInteractionIndex};
@@ -46,7 +46,7 @@ pub struct ImpulseJointSet {
     joint_ids: Arena<TemporaryInteractionIndex>,
     joint_graph: InteractionGraph<RigidBodyHandle, ImpulseJoint>,
     /// A set of rigid-body handles to wake-up during the next timestep.
-    pub(crate) to_wake_up: HashMap<RigidBodyHandle, ()>,
+    pub(crate) to_wake_up: HashSet<RigidBodyHandle>,
 }
 
 impl ImpulseJointSet {
@@ -56,7 +56,7 @@ impl ImpulseJointSet {
             rb_graph_ids: Coarena::new(),
             joint_ids: Arena::new(),
             joint_graph: InteractionGraph::new(),
-            to_wake_up: HashMap::default(),
+            to_wake_up: HashSet::default(),
         }
     }
 
@@ -158,8 +158,8 @@ impl ImpulseJointSet {
         let joint = self.joint_graph.graph.edge_weight_mut(*id);
         if wake_up_connected_bodies {
             if let Some(joint) = &joint {
-                self.to_wake_up.insert(joint.body1, ());
-                self.to_wake_up.insert(joint.body2, ());
+                self.to_wake_up.insert(joint.body1);
+                self.to_wake_up.insert(joint.body2);
             }
         }
         joint
@@ -285,8 +285,8 @@ impl ImpulseJointSet {
         self.joint_ids[handle] = self.joint_graph.add_edge(graph_index1, graph_index2, joint);
 
         if wake_up {
-            self.to_wake_up.insert(body1, ());
-            self.to_wake_up.insert(body2, ());
+            self.to_wake_up.insert(body1);
+            self.to_wake_up.insert(body2);
         }
 
         ImpulseJointHandle(handle)
@@ -337,10 +337,10 @@ impl ImpulseJointSet {
 
         if wake_up {
             if let Some(rb_handle) = self.joint_graph.graph.node_weight(endpoints.0) {
-                self.to_wake_up.insert(*rb_handle, ());
+                self.to_wake_up.insert(*rb_handle);
             }
             if let Some(rb_handle) = self.joint_graph.graph.node_weight(endpoints.1) {
-                self.to_wake_up.insert(*rb_handle, ());
+                self.to_wake_up.insert(*rb_handle);
             }
         }
 
@@ -390,8 +390,8 @@ impl ImpulseJointSet {
                     }
 
                     // Wake up the attached bodies.
-                    self.to_wake_up.insert(h1, ());
-                    self.to_wake_up.insert(h2, ());
+                    self.to_wake_up.insert(h1);
+                    self.to_wake_up.insert(h2);
                 }
 
                 if let Some(other) = self.joint_graph.remove_node(deleted_id) {
diff --git a/src/dynamics/joint/multibody_joint/multibody_joint_set.rs b/src/dynamics/joint/multibody_joint/multibody_joint_set.rs
index d315729..fefa927 100644
--- a/src/dynamics/joint/multibody_joint/multibody_joint_set.rs
+++ b/src/dynamics/joint/multibody_joint/multibody_joint_set.rs
@@ -1,4 +1,4 @@
-use parry::utils::hashmap::HashMap;
+use parry::utils::hashset::HashSet;
 
 use crate::data::{Arena, Coarena, Index};
 use crate::dynamics::joint::MultibodyLink;
@@ -96,7 +96,7 @@ pub struct MultibodyJointSet {
     // NOTE: this is mostly for the island extraction. So perhaps we won’t need
     //       that any more in the future when we improve our island builder.
     pub(crate) connectivity_graph: InteractionGraph<RigidBodyHandle, ()>,
-    pub(crate) to_wake_up: HashMap<RigidBodyHandle, ()>,
+    pub(crate) to_wake_up: HashSet<RigidBodyHandle>,
 }
 
 impl MultibodyJointSet {
@@ -106,7 +106,7 @@ impl MultibodyJointSet {
             multibodies: Arena::new(),
             rb2mb: Coarena::new(),
             connectivity_graph: InteractionGraph::new(),
-            to_wake_up: HashMap::default(),
+            to_wake_up: HashSet::default(),
         }
     }
 
@@ -203,8 +203,8 @@ impl MultibodyJointSet {
         multibody1.append(mb2, link1.id, MultibodyJoint::new(data.into(), kinematic));
 
         if wake_up {
-            self.to_wake_up.insert(body1, ());
-            self.to_wake_up.insert(body2, ());
+            self.to_wake_up.insert(body1);
+            self.to_wake_up.insert(body2);
         }
 
         // Because each rigid-body can only have one parent link,
@@ -227,8 +227,8 @@ impl MultibodyJointSet {
                     .remove_edge(parent_graph_id, removed.graph_id);
 
                 if wake_up {
-                    self.to_wake_up.insert(RigidBodyHandle(handle.0), ());
-                    self.to_wake_up.insert(parent_rb, ());
+                    self.to_wake_up.insert(RigidBodyHandle(handle.0));
+                    self.to_wake_up.insert(parent_rb);
                 }
 
                 // TODO: remove the node if it no longer has any attached edges?
@@ -270,7 +270,7 @@ impl MultibodyJointSet {
                 let rb_handle = link.rigid_body;
 
                 if wake_up {
-                    self.to_wake_up.insert(rb_handle, ());
+                    self.to_wake_up.insert(rb_handle);
                 }
 
                 // Remove the rigid-body <-> multibody mapping for this link.
@@ -296,8 +296,8 @@ impl MultibodyJointSet {
                 // There is a multibody_joint handle is equal to the second rigid-body’s handle.
                 articulations_to_remove.push(MultibodyJointHandle(rb2.0));
 
-                self.to_wake_up.insert(rb1, ());
-                self.to_wake_up.insert(rb2, ());
+                self.to_wake_up.insert(rb1);
+                self.to_wake_up.insert(rb2);
             }
 
             for articulation_handle in articulations_to_remove {
diff --git a/src/pipeline/physics_pipeline.rs b/src/pipeline/physics_pipeline.rs
index 8505618..91a737c 100644
--- a/src/pipeline/physics_pipeline.rs
+++ b/src/pipeline/physics_pipeline.rs
@@ -437,7 +437,7 @@ impl PhysicsPipeline {
             .drain()
             .chain(multibody_joints.to_wake_up.drain());
         for handle in impulse_joints_iterator {
-            islands.wake_up(bodies, handle.0, true);
+            islands.wake_up(bodies, handle, true);
         }
 
         // Apply modifications.