diff --git a/src/main/java/vazkii/psi/common/item/ItemVectorRuler.java b/src/main/java/vazkii/psi/common/item/ItemVectorRuler.java
index 1b7aa5c8..44330f5f 100644
--- a/src/main/java/vazkii/psi/common/item/ItemVectorRuler.java
+++ b/src/main/java/vazkii/psi/common/item/ItemVectorRuler.java
@@ -49,13 +49,12 @@ public InteractionResult useOn(UseOnContext ctx) {
 		BlockPos pos = ctx.getClickedPos();
 
 		ItemStack stack = ctx.getPlayer().getItemInHand(ctx.getHand());
-		int srcY = stack.getOrCreateTag().contains(TAG_SRC_Y) ? stack.getOrCreateTag().getInt(TAG_SRC_Y) : -1;
 
-		if(srcY == -1 || ctx.getPlayer().isShiftKeyDown()) {
+		if(!stack.getOrCreateTag().contains(TAG_SRC_Y) || ctx.getPlayer().isShiftKeyDown()) {
 			stack.getOrCreateTag().putInt(TAG_SRC_X, pos.getX());
 			stack.getOrCreateTag().putInt(TAG_SRC_Y, pos.getY());
 			stack.getOrCreateTag().putInt(TAG_SRC_Z, pos.getZ());
-			stack.getOrCreateTag().putInt(TAG_DST_Y, -1);
+			stack.removeTagKey(TAG_DST_Y);
 		} else {
 			stack.getOrCreateTag().putInt(TAG_DST_X, pos.getX());
 			stack.getOrCreateTag().putInt(TAG_DST_Y, pos.getY());
@@ -76,12 +75,12 @@ public Vector3 getVector(ItemStack stack) {
 		int srcY = stack.getOrCreateTag().getInt(TAG_SRC_Y);
 		int srcZ = stack.getOrCreateTag().getInt(TAG_SRC_Z);
 
-		int dstY = stack.getOrCreateTag().contains(TAG_DST_Y) ? stack.getOrCreateTag().getInt(TAG_DST_Y) : -1;
-		if(dstY == -1) {
+		if(!stack.getOrCreateTag().contains(TAG_DST_Y)) {
 			return new Vector3(srcX, srcY, srcZ);
 		}
 
 		int dstX = stack.getOrCreateTag().getInt(TAG_DST_X);
+		int dstY = stack.getOrCreateTag().getInt(TAG_DST_Y);
 		int dstZ = stack.getOrCreateTag().getInt(TAG_DST_Z);
 
 		return new Vector3(dstX - srcX, dstY - srcY, dstZ - srcZ);