diff --git a/include/jemalloc/internal/rtree.h b/include/jemalloc/internal/rtree.h
index 2eb726d6..c1fb90c4 100644
--- a/include/jemalloc/internal/rtree.h
+++ b/include/jemalloc/internal/rtree.h
@@ -260,7 +260,7 @@ rtree_set(rtree_t *rtree, uintptr_t key, const extent_node_t *val)
 			rtree_val_write(rtree, &node[subkey], val);
 			return (false);
 		}
-		assert(i < rtree->height - 1);
+		assert(i + 1 < rtree->height);
 		child = rtree_child_read(rtree, &node[subkey], i);
 		if (child == NULL)
 			return (true);
diff --git a/src/rtree.c b/src/rtree.c
index 47d9084e..af0d97e7 100644
--- a/src/rtree.c
+++ b/src/rtree.c
@@ -63,7 +63,7 @@ static void
 rtree_delete_subtree(rtree_t *rtree, rtree_node_elm_t *node, unsigned level)
 {
 
-	if (level < rtree->height - 1) {
+	if (level + 1 < rtree->height) {
 		size_t nchildren, i;
 
 		nchildren = ZU(1) << rtree->levels[level].bits;