diff --git a/backend/controller/sql/queries.sql b/backend/controller/sql/queries.sql
index 386d180fba..90ae6b2e55 100644
--- a/backend/controller/sql/queries.sql
+++ b/backend/controller/sql/queries.sql
@@ -35,6 +35,7 @@ WHERE deployment_id = $1;
 -- Create a new artefact and return the artefact ID.
 INSERT INTO artefacts (digest, content)
 VALUES ($1, $2)
+ON CONFLICT (digest) DO NOTHING
 RETURNING id;
 
 -- name: AssociateArtefactWithDeployment :exec
diff --git a/backend/controller/sql/queries.sql.go b/backend/controller/sql/queries.sql.go
index 79b2a680dd..7dc54f6320 100644
--- a/backend/controller/sql/queries.sql.go
+++ b/backend/controller/sql/queries.sql.go
@@ -176,6 +176,7 @@ func (q *Queries) CompleteEventForSubscription(ctx context.Context, name string,
 const createArtefact = `-- name: CreateArtefact :one
 INSERT INTO artefacts (digest, content)
 VALUES ($1, $2)
+ON CONFLICT (digest) DO NOTHING
 RETURNING id
 `