diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b8ad51c14d..e56b0ac9cd 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -1617,8 +1617,9 @@ RT_EXTEND_DOWN(RT_RADIX_TREE * tree, RT_PTR_ALLOC * parent_slot, uint64 key, int
 	}
 
 	/* Reserve slot for the value. */
+	Assert(shift == 0);
 	n4 = (RT_NODE_4 *) node.local;
-	n4->chunks[0] = RT_GET_KEY_CHUNK(key, shift);
+	n4->chunks[0] = RT_GET_KEY_CHUNK(key, 0);
 	n4->base.count = 1;
 
 	return &n4->children[0];