diff --git a/petri/src/lib.rs b/petri/src/lib.rs
index 5fcfb67..0eda324 100644
--- a/petri/src/lib.rs
+++ b/petri/src/lib.rs
@@ -60,7 +60,7 @@ pub enum RuleCellTo {
 	/// randomly choose from the group
 	GroupRandom(usize),
 	/// copy the cell from the corresponding input position
-	Copy(usize),
+	Copy(usize, usize),
 }
 
 impl SubRule {
@@ -197,7 +197,10 @@ impl Rule {
 				let mut new = b.clone();
 				for y in 0..new.height {
 					for x in 0..new.width {
-						let old = b.get(new.width - x - 1, y);
+						let mut old = b.get(new.width - x - 1, y);
+						if let (_, RuleCellTo::Copy(cx, _cy)) = &mut old {
+							*cx = new.width - *cx - 1;
+						}
 						new.set_both(x, y, old);
 					}
 				}
@@ -209,7 +212,10 @@ impl Rule {
 				let mut new = b.clone();
 				for y in 0..new.height {
 					for x in 0..new.width {
-						let old = b.get(x, new.height - y - 1);
+						let mut old = b.get(x, new.height - y - 1);
+						if let (_, RuleCellTo::Copy(_cx, cy)) = &mut old {
+							*cy = new.height - *cy - 1;
+						}
 						new.set_both(x, y, old);
 					}
 				}
@@ -222,7 +228,11 @@ impl Rule {
 				let mut new = b.clone();
 				for y in 0..new.height {
 					for x in 0..new.width {
-						let old = b.get(new.width - x - 1, new.height - y - 1);
+						let mut old = b.get(new.width - x - 1, new.height - y - 1);
+						if let (_, RuleCellTo::Copy(cx, cy)) = &mut old {
+							*cx = new.width - *cx - 1;
+							*cy = new.height - *cy - 1;
+						}
 						new.set_both(x, y, old);
 					}
 				}
@@ -235,7 +245,10 @@ impl Rule {
 				new.width = b.height;
 				for y in 0..new.height {
 					for x in 0..new.width {
-						let old = b.get(y, x);
+						let mut old = b.get(y, x);
+						if let (_, RuleCellTo::Copy(cx, cy)) = &mut old {
+							(*cx, *cy) = (*cy, *cx);
+						}
 						new.set_both(x, y, old);
 					}
 				}
@@ -280,6 +293,7 @@ impl Dish {
 		let mut default_rules = vec![
 			Rule {
 				enabled: true,
+				name: "fall".into(),
 				base: SubRule {
 					width: 1,
 					height: 2,
@@ -292,6 +306,7 @@ impl Dish {
 			},
 			Rule {
 				enabled: true,
+				name: "slide".into(),
 				base: SubRule {
 					width: 2,
 					height: 2,
@@ -384,8 +399,8 @@ impl Dish {
 							self.set_cell(px, py, cell);
 						}
 					}
-					RuleCellTo::Copy(index) => {
-						let cell = old_state[index];
+					RuleCellTo::Copy(x, y) => {
+						let cell = old_state[x + y * variant.width];
 						if let Some(cell) = cell {
 							// if the copy source is outside the world, do nothing
 							self.set_cell(px, py, cell);
diff --git a/uscope/src/main.rs b/uscope/src/main.rs
index 91c254d..fd23e43 100644
--- a/uscope/src/main.rs
+++ b/uscope/src/main.rs
@@ -495,11 +495,9 @@ fn rule_cell_edit_to(
 			let group = &groups[*group_id];
 			draw_group(ui, rect, group, cells);
 		}
-		RuleCellTo::Copy(index) => {
+		RuleCellTo::Copy(x, y) => {
 			let this = rect.center();
-			let x = *index % rule_width;
-			let y = *index / rule_width;
-			let target = origin + Vec2::from((x as f32, y as f32)) * CSIZE
+			let target = origin + Vec2::from((*x as f32, *y as f32)) * CSIZE
 				- Vec2::X * (CSIZE * (rule_width as f32 + 1.) + RESIZE_BUTTON_WIDTH * 2.)
 				+ Vec2::splat(CSIZE) * 0.5;
 			overlay_lines.push((this, target));
@@ -519,8 +517,15 @@ fn rule_cell_edit_to(
 				*group_id %= groups.len();
 				changed = true;
 			}
-			RuleCellTo::Copy(index) => {
-				*index = (*index + 1) % (rule_width * rule_height);
+			RuleCellTo::Copy(x, y) => {
+				*x += 1;
+				if *x >= rule_width {
+					*x = 0;
+					*y += 1;
+					if *y >= rule_height {
+						*y = 0;
+					}
+				}
 				changed = true;
 			}
 		}
@@ -536,9 +541,9 @@ fn rule_cell_edit_to(
 				*rule = RuleCellTo::GroupRandom(0);
 			}
 			RuleCellTo::GroupRandom(_) => {
-				*rule = RuleCellTo::Copy(0);
+				*rule = RuleCellTo::Copy(0, 0);
 			}
-			RuleCellTo::Copy(_) => {
+			RuleCellTo::Copy(_, _) => {
 				*rule = RuleCellTo::None;
 			}
 		}