diff --git a/09/index.ts b/09/index.ts
index 146dcee..4c272cc 100644
--- a/09/index.ts
+++ b/09/index.ts
@@ -102,6 +102,7 @@ while (rightCursor > 0) {
   );
   if (target.index < Infinity && target.index < rightCursor) {
     // slot exists; move the file, update the array, and update the space lists
+    // but only if the new location is actually to the right of our cursor
     sparceArray.splice(
       target.index,
       fileSize,
@@ -114,11 +115,9 @@ while (rightCursor > 0) {
     );
     spaces[target.size].shift();
     if (toNum(target.size) - fileSize > 0) {
-      spaces[(toNum(target.size) - fileSize).toString()].unshift(
-        target.index + fileSize
-      );
-      spaces[(toNum(target.size) - fileSize).toString()].sort((a, b) =>
-        a > b ? 1 : -1
+      let newGap = (toNum(target.size) - fileSize).toString();
+      spaces[newGap] = [...spaces[newGap], target.index + fileSize].sort(
+        (a, b) => (a > b ? 1 : -1)
       );
     }
   }