diff --git a/api.yaml b/api.yaml
index efc383b..e151071 100644
--- a/api.yaml
+++ b/api.yaml
@@ -2124,6 +2124,7 @@ components:
         eigenvector:
           # ontology: #character_node_eigenvector
           type: number
+          nullable: true
         weightedDegree:
           # ontology: #character_node_weighted_degree
           type: integer