diff --git a/go/seatdef/seatdef.go b/go/seatdef/seatdef.go
index f1336f3..6017b36 100644
--- a/go/seatdef/seatdef.go
+++ b/go/seatdef/seatdef.go
@@ -397,6 +397,8 @@ func (d Definition) check() Problems {
 			ps = append(ps, Problem{where + ".subject", "missing"})
 		case e.Subject == stream && e.Family == "":
 			ps = append(ps, Problem{where + ".subject", "a subject of the holder's own stream, and no family names that stream"})
+		case e.Subject == own && e.Family != "":
+			ps = append(ps, Problem{where + ".subject", "a family names the holder's own stream, so the event is under " + stream})
 		case e.Subject != own && e.Subject != stream:
 			ps = append(ps, Problem{where + ".subject", fmt.Sprintf("not %s, nor %s for an event kept in the holder's own stream", own, stream)})
 		}
diff --git a/go/seatdef/seatdef_test.go b/go/seatdef/seatdef_test.go
index e51f316..e385e38 100644
--- a/go/seatdef/seatdef_test.go
+++ b/go/seatdef/seatdef_test.go
@@ -45,6 +45,8 @@ func TestADefinitionIsReadStrictlyNamingWhatIsWrong(t *testing.T) {
 			`"subject":"mesh.stream.<holder>.event.verdict","family":"checker.asks"}],"family":`, 1), ""},
 		{"a holder's event on its own stream with no family", strings.Replace(whole, `"family":`, `"holder-events":[{"name":"verdict",`+
 			`"subject":"mesh.stream.<holder>.event.verdict"}],"family":`, 1), "no family names that stream"},
+		{"a holder's event kept in its own stream under its module's subjects", strings.Replace(whole, `"family":`, `"holder-events":[{"name":"verdict",`+
+			`"subject":"mesh.mod.<holder>.event.verdict","family":"checker.asks"}],"family":`, 1), "a family names the holder's own stream"},
 		{"a holder's event on a subject of no module", strings.Replace(whole, `"family":`, `"holder-events":[{"name":"verdict",`+
 			`"subject":"mesh.event.verdict"}],"family":`, 1), "holder-events[0].subject: not mesh.mod.<holder>.event.verdict"},
 		{"a verb twice", strings.Replace(listGrain, `]}`, `,{"name":"add"}]}`, 1), `"add" twice`},