diff --git a/src/gui/game/GameView.cpp b/src/gui/game/GameView.cpp
index b253d8a23..cdb51ac29 100644
--- a/src/gui/game/GameView.cpp
+++ b/src/gui/game/GameView.cpp
@@ -2290,8 +2290,8 @@ void GameView::OnDraw()
 				else if (type == PT_FILT)
 				{
 					sampleInfo << c->ElementResolve(type, ctype);
-					const char* filtModes[] = {"set colour", "AND", "OR", "subtract colour", "red shift", "blue shift", "no effect", "XOR", "NOT", "old QRTZ scattering"};
-					if (sample.particle.tmp>=0 && sample.particle.tmp<=9)
+					const char* filtModes[] = {"set colour", "AND", "OR", "subtract colour", "red shift", "blue shift", "no effect", "XOR", "NOT", "old QRTZ scattering", "variable red shift", "variable blue shift"};
+					if (sample.particle.tmp>=0 && sample.particle.tmp<=11)
 						sampleInfo << " (" << filtModes[sample.particle.tmp] << ")";
 					else
 						sampleInfo << " (unknown mode)";
diff --git a/src/simulation/elements/FILT.cpp b/src/simulation/elements/FILT.cpp
index 63ce3f068..802335adf 100644
--- a/src/simulation/elements/FILT.cpp
+++ b/src/simulation/elements/FILT.cpp
@@ -89,17 +89,17 @@ int Element_FILT::interactWavelengths(Particle* cpart, int origWl)
 		case 3:
 			return origWl & (~filtWl); //Subtract colour of filt from colour of photon
 		case 4:
-			{
-				int shift = int((cpart->temp-273.0f)*0.025f);
-				if (shift<=0) shift = 1;
-				return (origWl << shift) & mask; // red shift
-			}
+		{
+			int shift = int((cpart->temp-273.0f)*0.025f);
+			if (shift<=0) shift = 1;
+			return (origWl << shift) & mask; // red shift
+		}
 		case 5:
-			{
-				int shift = int((cpart->temp-273.0f)*0.025f);
-				if (shift<=0) shift = 1;
-				return (origWl >> shift) & mask; // blue shift
-			}
+		{
+			int shift = int((cpart->temp-273.0f)*0.025f);
+			if (shift<=0) shift = 1;
+			return (origWl >> shift) & mask; // blue shift
+		}
 		case 6:
 			return origWl; // No change
 		case 7:
@@ -113,6 +113,16 @@ int Element_FILT::interactWavelengths(Particle* cpart, int origWl)
 			int t3 = ((origWl & 0xFF0000)>>16)+(rand()%5)-2;
 			return (origWl & 0xFF000000) | (t3<<16) | (t2<<8) | t1;
 		}
+		case 10:
+		{
+			long long int lsb = filtWl & (-filtWl);
+			return (origWl * lsb) & 0x3FFFFFFF; //red shift
+		}
+		case 11:
+		{
+			long long int lsb = filtWl & (-filtWl);
+			return (origWl / lsb) & 0x3FFFFFFF; // blue shift
+		}
 		default:
 			return filtWl;
 	}