diff --git a/src/Renderer/Module/EdgeIterator/EdgeIterator.php b/src/Renderer/Module/EdgeIterator/EdgeIterator.php
index 01f692c..91d3850 100644
--- a/src/Renderer/Module/EdgeIterator/EdgeIterator.php
+++ b/src/Renderer/Module/EdgeIterator/EdgeIterator.php
@@ -122,10 +122,11 @@ private function xorEdge(Edge $path) : void
             }
 
             $x = $points[$i][0];
-            $minY = min($y1, $y);
+            $offset = $this->width * min($y1, $y);
 
-            for ($j = $x; $j < $maxX; ++$j) {
-                $this->flip($j, $minY);
+            // The cells flipped here are always inside of the matrix, so they need no bounds checks
+            for ($j = $offset + $x, $end = $offset + $maxX; $j < $end; ++$j) {
+                $this->bytes[$j] = 1 === $this->bytes[$j] ? 0 : 1;
             }
 
             $y1 = $y;
@@ -150,11 +151,4 @@ private function pointOf(int $i) : array
         $y = intdiv($i, $this->width);
         return [$i - $y * $this->width, $y];
     }
-
-    private function flip(int $x, int $y) : void
-    {
-        $this->bytes[$this->width * $y + $x] = (
-            $this->isSet($x, $y) ? 0 : 1
-        );
-    }
 }
diff --git a/src/Renderer/Module/SquareModule.php b/src/Renderer/Module/SquareModule.php
index 8cf1d0b..9bb1725 100644
--- a/src/Renderer/Module/SquareModule.php
+++ b/src/Renderer/Module/SquareModule.php
@@ -30,13 +30,16 @@ public function createPath(ByteMatrix $matrix) : Path
         foreach (new EdgeIterator($matrix) as $edge) {
             $points = $edge->getSimplifiedPoints();
             $length = count($points);
-            $path = $path->move($points[0][0], $points[0][1]);
+
+            // Each operation added to a path copies the ones before it, so every edge is built as a short path of its
+            // own first, rather than one operation at a time onto the whole path
+            $edgePath = (new Path())->move($points[0][0], $points[0][1]);
 
             for ($i = 1; $i < $length; ++$i) {
-                $path = $path->line($points[$i][0], $points[$i][1]);
+                $edgePath = $edgePath->line($points[$i][0], $points[$i][1]);
             }
 
-            $path = $path->close();
+            $path = $path->append($edgePath->close());
         }
 
         return $path;