diff --git a/sync/optimistic.md b/sync/optimistic.md
index edb54ab27..ccae7d093 100644
--- a/sync/optimistic.md
+++ b/sync/optimistic.md
@@ -85,7 +85,7 @@ def is_optimistic(block: BeaconBlock) -> bool:
 
 ```python
 def latest_valid_ancestor(block: BeaconBlock) -> BeaconBlock:
-    while block.parent_root != Root():
+    while True:
         if not is_optimistic(block) or block.parent_root == Root():
 	        return block
         block = get_block(block.parent_root)