diff --git a/vocabularies/common/certainty-level.json b/vocabularies/common/certainty-level.json
index 06b0605..6306632 100644
--- a/vocabularies/common/certainty-level.json
+++ b/vocabularies/common/certainty-level.json
@@ -32,6 +32,7 @@
   "type": "certainty-level",
   "uuid": "bc5d96ea-f579-45de-9b6e-7d3c64035718",
   "author": ["MISP","CIA"],
+  "source": "MISP Project",
   "description": "Certainty level of an associated element or cluster.",
   "version": 1
 }