diff --git a/include/openmc/geometry.h b/include/openmc/geometry.h
index 6947201a2..a7ac53ea3 100644
--- a/include/openmc/geometry.h
+++ b/include/openmc/geometry.h
@@ -7,7 +7,7 @@
 #include <vector>
 
 #include "openmc/particle.h"
-//#include "openmc/tallies/filter.h"
+#include "openmc/tallies/filter.h"
 
 
 namespace openmc {
diff --git a/include/openmc/simulation.h b/include/openmc/simulation.h
index 21414ff67..e6f82e7f6 100644
--- a/include/openmc/simulation.h
+++ b/include/openmc/simulation.h
@@ -65,8 +65,6 @@ void initialize_generation();
 
 void initialize_history(Particle* p, int64_t index_source);
 
-void transport_history_based_single_particle(Particle& p);
-
 //! Finalize a batch
 //!
 //! Handles synchronization and accumulation of tallies, calculation of Shannon
@@ -86,6 +84,13 @@ void broadcast_results();
 
 void free_memory_simulation();
 
+//! Simulate a single particle history (and all generated secondary particles,
+//!  if enabled), from birth to death
+void transport_history_based_single_particle(Particle& p);
+
+//! Simulate all particle histories using history-based parallelism
+void transport_history_based();
+
 } // namespace openmc
 
 #endif // OPENMC_SIMULATION_H
diff --git a/src/simulation.cpp b/src/simulation.cpp
index cb603c403..6ac776639 100644
--- a/src/simulation.cpp
+++ b/src/simulation.cpp
@@ -37,31 +37,6 @@
 
 namespace openmc {
 
-void transport_history_based_single_particle(Particle& p)
-{
-  while(true) {
-    p.event_calculate_xs();
-    p.event_advance();
-    if( p.collision_distance_ > p.boundary_.distance ) 
-      p.event_cross_surface();
-    else
-      p.event_collide();
-    p.event_revive_from_secondary();
-    if(!p.alive_)
-      break;
-  }
-  p.event_death();
-}
-
-void transport_history_based()
-{
-  #pragma omp parallel for schedule(runtime)
-  for (int64_t i_work = 1; i_work <= simulation::work_per_rank; ++i_work) {
-    Particle p;
-    initialize_history(&p, i_work);
-    transport_history_based_single_particle(p);
-  }
-}
 
 } // namespace openmc
 
@@ -590,4 +565,30 @@ void free_memory_simulation()
   simulation::entropy.clear();
 }
 
+void transport_history_based_single_particle(Particle& p)
+{
+  while(true) {
+    p.event_calculate_xs();
+    p.event_advance();
+    if( p.collision_distance_ > p.boundary_.distance ) 
+      p.event_cross_surface();
+    else
+      p.event_collide();
+    p.event_revive_from_secondary();
+    if(!p.alive_)
+      break;
+  }
+  p.event_death();
+}
+
+void transport_history_based()
+{
+  #pragma omp parallel for schedule(runtime)
+  for (int64_t i_work = 1; i_work <= simulation::work_per_rank; ++i_work) {
+    Particle p;
+    initialize_history(&p, i_work);
+    transport_history_based_single_particle(p);
+  }
+}
+
 } // namespace openmc