diff --git a/src/simulation/Simulation.cpp b/src/simulation/Simulation.cpp
index 537d6fd4b..30f27acc4 100644
--- a/src/simulation/Simulation.cpp
+++ b/src/simulation/Simulation.cpp
@@ -3330,9 +3330,9 @@ void Simulation::RecalcFreeParticles(bool do_life_dec)
 					photons[y][x] = PMAP(i, t);
 				else
 				{
-					// Particles are sometimes allowed to go inside INVS and FILT
+					// Particles are sometimes allowed to go inside INVS, FILT, and PAPR
 					// To make particles collide correctly when inside these elements, these elements must not overwrite an existing pmap entry from particles inside them
-					if (!pmap[y][x] || (t!=PT_INVIS && t!= PT_FILT))
+					if (!pmap[y][x] || (t!=PT_INVIS && t!= PT_FILT && t != PT_PAPR))
 						pmap[y][x] = PMAP(i, t);
 					// (there are a few exceptions, including energy particles - currently no limit on stacking those)
 					if (t!=PT_THDR && t!=PT_EMBR && t!=PT_FIGH && t!=PT_PLSM)
diff --git a/src/simulation/SimulationData.cpp b/src/simulation/SimulationData.cpp
index a125f3925..f7b3a86db 100644
--- a/src/simulation/SimulationData.cpp
+++ b/src/simulation/SimulationData.cpp
@@ -187,7 +187,7 @@ void SimulationData::init_can_move()
 			can_move[movingType][PT_SAWD] = 0;
 
 		// Let most non-solids pass through PAPR
-        if (elements[movingType].Properties & (TYPE_GAS | TYPE_PART | TYPE_LIQUID))
+        if (elements[movingType].Properties & (TYPE_GAS | TYPE_PART | TYPE_LIQUID) && (movingType != PT_FIRE && movingType != PT_SMKE))
             can_move[movingType][PT_PAPR] = 2;
 	}
 	//a list of lots of things PHOT can move through