diff --git a/core/src/main/java/com/shatteredpixel/shatteredpixeldungeon/levels/rooms/special/SpecialRoom.java b/core/src/main/java/com/shatteredpixel/shatteredpixeldungeon/levels/rooms/special/SpecialRoom.java
index 14769f5a5..779501fea 100644
--- a/core/src/main/java/com/shatteredpixel/shatteredpixeldungeon/levels/rooms/special/SpecialRoom.java
+++ b/core/src/main/java/com/shatteredpixel/shatteredpixeldungeon/levels/rooms/special/SpecialRoom.java
@@ -131,8 +131,8 @@ public abstract class SpecialRoom extends Room {
 	public static void initForFloor(){
 		floorSpecials = (ArrayList<Class<?extends Room>>) runSpecials.clone();
 		
-		//laboratory rooms spawn at set intervals every chapter
-		if (Dungeon.depth%5 == (Dungeon.seed%3 + 2)){
+		//laboratory rooms spawn at set intervals every chapter, on 3rd or 4th floor
+		if (Dungeon.depth%5 == (Dungeon.seed%2 + 3)){
 			floorSpecials.add(0, LaboratoryRoom.class);
 		}
 	}