diff --git a/src/main/java/com/cricketcraft/chisel/Features.java b/src/main/java/com/cricketcraft/chisel/Features.java
index cd612185..88884a20 100644
--- a/src/main/java/com/cricketcraft/chisel/Features.java
+++ b/src/main/java/com/cricketcraft/chisel/Features.java
@@ -2572,7 +2572,7 @@ public enum Features {
 	
 	private static void registerSlabTop(Block bottom, Block top) {
 		String name = Block.blockRegistry.getNameForObject(bottom);
-		name = name.substring(name.indexOf(':')) + "_top";
+		name = name.substring(name.indexOf(':') + 1) + "_top";
 		GameRegistry.registerBlock(top, ItemCarvableSlab.class, name);
 	}
 }
diff --git a/src/main/java/com/cricketcraft/chisel/item/ItemCarvableSlab.java b/src/main/java/com/cricketcraft/chisel/item/ItemCarvableSlab.java
index a7e02f45..668d45ed 100644
--- a/src/main/java/com/cricketcraft/chisel/item/ItemCarvableSlab.java
+++ b/src/main/java/com/cricketcraft/chisel/item/ItemCarvableSlab.java
@@ -36,7 +36,7 @@ public class ItemCarvableSlab extends ItemCarvable {
 
 		boolean metaEquals = world.getBlockMetadata(x2, y2, z2) == meta;
 		// if the metadata at the place target matches, and the block there matches either the top of bottom slab, try to fill in the rest of the block
-		if (metaEquals && ((at == block.top && (dir == ForgeDirection.DOWN || hy == 1.0D)) || (at == block.bottom && (dir == ForgeDirection.UP || hy == 0)))) {
+		if (metaEquals && ((at == block.top && (hy <= 0.5D || hy == 1.0D)) || (at == block.bottom && (hy > 0.5D || hy == 0)))) {
 			place(stack, world, x2, y2, z2, block.master, meta);
 			return true;
 		}