diff --git a/internal/api/dhcp/digest_test.go b/internal/api/dhcp/digest_test.go
index fe5dd29..f8a0510 100644
--- a/internal/api/dhcp/digest_test.go
+++ b/internal/api/dhcp/digest_test.go
@@ -1,6 +1,8 @@
 package dhcpapi
 
 import (
+	"encoding/json"
+	"strings"
 	"testing"
 )
 
@@ -171,3 +173,13 @@ func TestCanonical_SortsHostsByMAC(t *testing.T) {
 		t.Errorf("hosts = %v, want sorted by mac", got.Hosts)
 	}
 }
+
+func TestResponse_ServedIsAlwaysOnTheWire(t *testing.T) {
+	raw, err := json.Marshal(Response{OK: true, Served: false})
+	if err != nil {
+		t.Fatalf("Marshal: %v", err)
+	}
+	if !strings.Contains(string(raw), `"served":false`) {
+		t.Errorf("response = %s, want an explicit served:false — omitting it makes \"not served\" indistinguishable from a missing field when probing by hand", raw)
+	}
+}
diff --git a/internal/api/dhcp/models.go b/internal/api/dhcp/models.go
index b0268cf..d454194 100644
--- a/internal/api/dhcp/models.go
+++ b/internal/api/dhcp/models.go
@@ -54,5 +54,5 @@ type Response struct {
 	State  *State `json:"state,omitempty"`
 	Digest string `json:"digest,omitempty"`
 	Lease  *Lease `json:"lease,omitempty"`
-	Served bool   `json:"served,omitempty"`
+	Served bool   `json:"served"`
 }