diff --git a/packages/utils/src/flatTree.ts b/packages/utils/src/flatTree.ts
index d9351ee..9b77c21 100644
--- a/packages/utils/src/flatTree.ts
+++ b/packages/utils/src/flatTree.ts
@@ -88,7 +88,7 @@ function decode_recursive(dense: number[] | Int32Array, index = 0) {
           dense,
           index
         );
-        decoded.push(p);
+        decoded.push(p as number[]);
         index = nextIndex + 1;
         nextBracketIndex = _nextBracketIndex;
       } else {