1 files changed, 4 insertions, 0 deletions
diff --git a/node.go b/node.go
index 1bc889d..14bf136 100644
--- a/node.go
+++ b/node.go
@@ -98,6 +98,8 @@ func (n *node) prevSibling() *node {
 
 // put inserts a key/value.
 func (n *node) put(oldKey, newKey, value []byte, pgid pgid, flags uint32) {
+	_assert(pgid < n.bucket.tx.meta.pgid, "pgid (%d) above high water mark (%d)", pgid, n.bucket.tx.meta.pgid)
+
 	// Find insertion index.
 	index := sort.Search(len(n.inodes), func(i int) bool { return bytes.Compare(n.inodes[i].key, oldKey) != -1 })
 
@@ -278,6 +280,7 @@ func (n *node) spill() error {
 		}
 
 		// Write the node.
+		_assert(p.id < tx.meta.pgid, "pgid (%d) above high water mark (%d)", p.id, tx.meta.pgid)
 		node.pgid = p.id
 		node.write(p)
 
@@ -307,6 +310,7 @@ func (n *node) spill() error {
 		}
 
 		// Write the new root.
+		_assert(p.id < tx.meta.pgid, "pgid (%d) above high water mark (%d)", p.id, tx.meta.pgid)
 		parent.pgid = p.id
 		parent.write(p)
 	}