diff --git a/src/dexorder/blocks.py b/src/dexorder/blocks.py
index e1d4d20..f8377da 100644
--- a/src/dexorder/blocks.py
+++ b/src/dexorder/blocks.py
@@ -43,7 +43,7 @@ async def _cache_fetch(key: tuple[int, Union[int,bytes]], default: Union[Block,
         result = await fetch_block_by_number(blockid, chain_id=chain_id)
     else:
         result = await fetch_block(blockid, chain_id=chain_id)
-    if result is not None:
+    if result is None:
         # log.debug(f'Could not lookup block {blockid}')
         return None # do not cache
     _lru[key] = result