diff --git a/core/blockchain.go b/core/blockchain.go
index 3a9caf01e0346a5abd7e27570114087889bb26a0..bcd53d49873fca53c181a7ea811095888229af92 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -445,7 +445,11 @@ func (bc *BlockChain) repair(head **types.Block) error {
 			return nil
 		}
 		// Otherwise rewind one block and recheck state availability there
-		(*head) = bc.GetBlock((*head).ParentHash(), (*head).NumberU64()-1)
+		block := bc.GetBlock((*head).ParentHash(), (*head).NumberU64()-1)
+		if block == nil {
+			return fmt.Errorf("missing block %d [%x]", (*head).NumberU64()-1, (*head).ParentHash())
+		}
+		(*head) = block
 	}
 }