diff --git a/birdvisu/annotations/__init__.py b/birdvisu/annotations/__init__.py
index bef0c90..667572c 100644
--- a/birdvisu/annotations/__init__.py
+++ b/birdvisu/annotations/__init__.py
@@ -22,7 +22,7 @@ indirections to iterating over all annotation of a particular vertex/edge. We
 believe that the latter is less common operation, so this seems like a good
 approach."""
 
-from ..topo_v3 import TopologyV3, VertexID, Edge
+from ..topo_v3 import TopologyV3, VertexID, Edge, VertexFinder
 from collections import defaultdict
 from collections.abc import Hashable
 from dataclasses import dataclass, field
@@ -33,6 +33,8 @@ class AnnotatedTopology:
 	def __init__(self, topology):
 		if not topology.frozen: raise ValueError('Can only annotate frozen topologies.')
 		self.topology = topology
+		self.finder = VertexFinder()
+		self.finder.add_topology(topology)
 		self.annotations: dict['AnnotatorID', 'Annotation'] = dict()
 		# Keeping track of dependencies
 		self.running_annotations = set()
diff --git a/birdvisu/topo_v3.py b/birdvisu/topo_v3.py
index f11e59f..b25ccc4 100644
--- a/birdvisu/topo_v3.py
+++ b/birdvisu/topo_v3.py
@@ -235,7 +235,6 @@ class Edge:
 	# adding them to a topology.
 	virtual: bool = False
 
-@dataclass
 class VertexFinder:
 	"""Tracker of presence of vertices in topologies.