diff --git a/include/openmc/event.h b/include/openmc/event.h
index 9a9615d73..44c08b27b 100644
--- a/include/openmc/event.h
+++ b/include/openmc/event.h
@@ -28,30 +28,13 @@ struct QueueItem{
   int64_t material;    //!< material that particle is in
   double E;            //!< particle energy
 
-  // Comparator sorts by particle type, then by material type, then by energy
+  // Compare by particle type, then by material type, then by energy
+  // TODO: Currently, material IDs are not usually unique to material
+  // types. When unique material type IDs are available, we can alter the
+  // material field in this struct to contain the material type instead.
   bool operator<(const QueueItem& rhs) const
   {
-    // First, compare by particle type
-    if (type < rhs.type) {
-      return true;
-    } else if (type > rhs.type) {
-      return false;
-    }
-
-    // If we have reached this point, we have the same particle types.
-    
-    // Next, compare by material:
-    // TODO: Currently, material IDs are not usually unique to material
-    // types. When unique material type IDs are available, we can alter the
-    // material field in this struct to contain the material type instead.
-    if( material < rhs.material)
-      return true;
-    if( material > rhs.material)
-      return false;
-
-    // At this point, we have the same particle type, in the same material.
-    // Now, compare by energy.
-    return (E < rhs.E);
+    return std::tie(type, material, E) < std::tie(rhs.type, rhs.material, rhs.E);
   }
 };
 
@@ -102,7 +85,7 @@ void free_event_queues(void);
 //! \param length A reference to the length variable for the queue
 //! \param p A pointer to the particle
 //! \param buffer_idx The particle's actual index in the particle buffer
-void enqueue_particle(QueueItem* queue, int64_t& length, Particle* p,
+void enqueue_particle(QueueItem* queue, int64_t& length, const Particle* p,
     int64_t buffer_idx);
 
 //! Enqueues a particle based on if it is in fuel or a non-fuel material
diff --git a/src/event.cpp b/src/event.cpp
index 2d94234e7..d3dde9c71 100644
--- a/src/event.cpp
+++ b/src/event.cpp
@@ -52,7 +52,7 @@ void free_event_queues(void)
   simulation::particles.reset();
 }
 
-void enqueue_particle(QueueItem* queue, int64_t& length, Particle* p,
+void enqueue_particle(QueueItem* queue, int64_t& length, const Particle* p,
     int64_t buffer_idx)
 {
   int64_t idx;
@@ -73,8 +73,8 @@ void dispatch_xs_event(int64_t buffer_idx)
     enqueue_particle(simulation::calculate_nonfuel_xs_queue.get(),
         simulation::calculate_nonfuel_xs_queue_length, p, buffer_idx);
   } else {
-      enqueue_particle(simulation::calculate_fuel_xs_queue.get(),
-          simulation::calculate_fuel_xs_queue_length, p, buffer_idx);
+    enqueue_particle(simulation::calculate_fuel_xs_queue.get(),
+        simulation::calculate_fuel_xs_queue_length, p, buffer_idx);
   }
 }
 
diff --git a/src/settings.cpp b/src/settings.cpp
index acd635047..e942ed2df 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -132,7 +132,8 @@ void get_run_parameters(pugi::xml_node node_base)
   
   // Get maximum number of in flight particles for event-based mode
   if (check_for_node(node_base, "max_in_flight_particles")) {
-    max_in_flight_particles = std::stoll(get_node_value(node_base, "max_in_flight_particles"));
+    max_in_flight_particles = std::stoll(get_node_value(node_base,
+      "max_in_flight_particles"));
   }
 
   // Get number of basic batches