diff --git a/src/funtracks/candidate_graph/utils.py b/src/funtracks/candidate_graph/utils.py
index 57b30a5..7147de5 100644
--- a/src/funtracks/candidate_graph/utils.py
+++ b/src/funtracks/candidate_graph/utils.py
@@ -65,6 +65,8 @@ def nodes_from_segmentation(
             attrs[NodeAttr.SEG_ID.value] = regionprop.label
             centroid = regionprop.centroid  # [z,] y, x
             attrs[NodeAttr.POS.value] = centroid
+            if node_id in cand_graph.nodes:
+                raise ValueError("Duplicate values found among nodes")
             cand_graph.add_node(node_id, **attrs)
             nodes_in_frame.append(node_id)
         if nodes_in_frame:
diff --git a/tests/candidate_graph/test_compute_graph.py b/tests/candidate_graph/test_compute_graph.py
index df35afa..0e7f049 100644
--- a/tests/candidate_graph/test_compute_graph.py
+++ b/tests/candidate_graph/test_compute_graph.py
@@ -50,6 +50,15 @@ def test_graph_from_segmentation_3d(segmentation_3d, graph_3d):
         assert pytest.approx(cand_graph.edges[edge], abs=0.01) == graph_3d.edges[edge]
 
 
+def test_graph_from_segmentation_with_duplicate_nodes(segmentation_2d):
+    segmentation_2d[1][20:25, 20:25] = 1  # add a duplicate label to another time point
+    with pytest.raises(ValueError, match="Duplicate values found among nodes"):
+        compute_graph_from_seg(
+            segmentation=segmentation_2d,
+            max_edge_distance=100,
+        )
+
+
 def test_graph_from_points_list():
     points_list = np.array(
         [