diff --git a/policy/diamond/policy/session/session.rego b/policy/diamond/policy/session/session.rego
index 8339b18..1215271 100644
--- a/policy/diamond/policy/session/session.rego
+++ b/policy/diamond/policy/session/session.rego
@@ -56,8 +56,11 @@ write_to_beamline_visit if {
 	matches_beamline
 }
 
-user_sessions contains session if {
-	subject := token.claims.fedid
+user_sessions contains user_session if {
 	some session in data.diamond.data.sessions
-	access_session(subject, session.proposal_number, session.visit_number)
+	access_session(token.claims.fedid, session.proposal_number, session.visit_number)
+	user_session := sprintf(
+		"\"proposal_number\": %d, \"visit_number\": %d, \"beamline\": %s",
+		[session.proposal_number, session.visit_number, session.beamline],
+	)
 }
diff --git a/policy/diamond/policy/session/session_test.rego b/policy/diamond/policy/session/session_test.rego
index 9d40bb9..7202a0d 100644
--- a/policy/diamond/policy/session/session_test.rego
+++ b/policy/diamond/policy/session/session_test.rego
@@ -186,18 +186,18 @@ test_user_session_tags if {
 	session.user_sessions == set() with data.diamond.data as diamond_data
 		with data.diamond.policy.token.claims as {"fedid": "oscar"}
 	session.user_sessions == {
-		{"proposal_number": 1, "visit_number": 2, "beamline": "b07"},
-		{"proposal_number": 1, "visit_number": 1, "beamline": "i03"},
+		"\"proposal_number\": 1, \"visit_number\": 2, \"beamline\": b07",
+		"\"proposal_number\": 1, \"visit_number\": 1, \"beamline\": i03",
 	} with data.diamond.data as diamond_data
 		with data.diamond.policy.token.claims as {"fedid": "alice"}
 	session.user_sessions == {
-		{"proposal_number": 1, "visit_number": 2, "beamline": "b07"},
-		{"proposal_number": 1, "visit_number": 1, "beamline": "i03"},
+		"\"proposal_number\": 1, \"visit_number\": 2, \"beamline\": b07",
+		"\"proposal_number\": 1, \"visit_number\": 1, \"beamline\": i03",
 	} with data.diamond.data as diamond_data
 		with data.diamond.policy.token.claims as {"fedid": "bob"}
 	session.user_sessions == {
-		{"proposal_number": 1, "visit_number": 2, "beamline": "b07"},
-		{"proposal_number": 1, "visit_number": 1, "beamline": "i03"},
+		"\"proposal_number\": 1, \"visit_number\": 2, \"beamline\": b07",
+		"\"proposal_number\": 1, \"visit_number\": 1, \"beamline\": i03",
 	} with data.diamond.data as diamond_data
 		with data.diamond.policy.token.claims as {"fedid": "carol"}
 }