diff --git a/core/chain_indexer.go b/core/chain_indexer.go
index b8c588efe3..7e7500dc85 100644
--- a/core/chain_indexer.go
+++ b/core/chain_indexer.go
@@ -201,7 +201,11 @@ func (c *ChainIndexer) eventLoop(currentHeader *types.Header, events chan ChainE
 			}
 			header := ev.Block.Header()
 			if header.ParentHash != prevHash {
-				c.newHead(FindCommonAncestor(c.chainDb, prevHeader, header).Number.Uint64(), true)
+				// Reorg to the common ancestor (might not exist in light sync mode, skip reorg then)
+				// TODO(karalabe, zsfelfoldi): This seems a bit brittle, can we detect this case explicitly?
+				if h := FindCommonAncestor(c.chainDb, prevHeader, header); h != nil {
+					c.newHead(h.Number.Uint64(), true)
+				}
 			}
 			c.newHead(header.Number.Uint64(), false)