diff --git a/src/simulation/Elements.h b/src/simulation/Elements.h
index 9c383c264..ec1e7df14 100644
--- a/src/simulation/Elements.h
+++ b/src/simulation/Elements.h
@@ -15,6 +15,7 @@
 #define TYPE_SOLID			0x00004  //4 Solids
 #define TYPE_GAS			0x00008  //8 Gasses (Includes plasma)
 #define TYPE_ENERGY			0x00010  //16 Energy (Thunder, Light, Neutrons etc.)
+#define STATE_FLAGS			0x0001F
 #define PROP_CONDUCTS		0x00020  //32 Conducts electricity
 #define PROP_BLACK			0x00040  //64 Absorbs Photons (not currently implemented or used, a photwl attribute might be better)
 #define PROP_NEUTPENETRATE	0x00080  //128 Penetrated by neutrons
diff --git a/src/simulation/simtools/Mix.cpp b/src/simulation/simtools/Mix.cpp
index 30eccf227..185be9931 100755
--- a/src/simulation/simtools/Mix.cpp
+++ b/src/simulation/simtools/Mix.cpp
@@ -32,7 +32,7 @@ int Tool_Mix::Perform(Simulation * sim, Particle * cpart, int x, int y, float st
 	if(!thatPart)
 		return 0;
 
-	if(!(sim->elements[thatPart&0xFF].Properties & (TYPE_PART | TYPE_LIQUID | TYPE_GAS)))
+	if ((sim->elements[thisPart&0xFF].Properties&STATE_FLAGS) != (sim->elements[thatPart&0xFF].Properties&STATE_FLAGS))
 		return 0;
 
 	sim->pmap[y][x] = thatPart;