diff --git a/eth/handler.go b/eth/handler.go
index 62befdbd09..aa01b444ef 100644
--- a/eth/handler.go
+++ b/eth/handler.go
@@ -509,6 +509,7 @@ func (h *handler) runDiffExtension(peer *diff.Peer, handler diff.Handler) error
 
 	if err := h.peers.registerDiffExtension(peer); err != nil {
 		peer.Log().Error("Diff extension registration failed", "err", err)
+		peer.Close()
 		return err
 	}
 	return handler(peer)
diff --git a/eth/handler_diff.go b/eth/handler_diff.go
index 6d5436bf9a..99f174ecd3 100644
--- a/eth/handler_diff.go
+++ b/eth/handler_diff.go
@@ -45,6 +45,7 @@ func (h *diffHandler) RunPeer(peer *diff.Peer, hand diff.Handler) error {
 			wait <- peer
 		}
 		ps.lock.Unlock()
+		peer.Close()
 		return err
 	}
 	return (*handler)(h).runDiffExtension(peer, hand)