diff --git a/src/orb/ingest.ts b/src/orb/ingest.ts
index f787430091..dd52d104b4 100644
--- a/src/orb/ingest.ts
+++ b/src/orb/ingest.ts
@@ -93,10 +93,21 @@ export async function handleOrbIngest(body: string, db: D1Database): Promise<Orb
   }
 
   const { instance_id, events, health } = payload as OrbIngestPayload;
-  // #4933: an empty batch is only valid when it's carrying a health-only ping (the hourly export still
-  // has to report health even in a tick with nothing new to export) -- a truly empty, health-less payload
-  // stays rejected exactly as before.
-  const healthy = typeof health === "object" && health !== null && typeof health.ok === "boolean" ? (health.ok ? 1 : 0) : null;
+  // #4933: a `health` key that IS present must be well-formed, whether or not `events` also carries real
+  // outcome rows -- rejecting only when events is also empty would silently drop a malformed health report
+  // from a sender that also has real events to export, instead of surfacing the sender's bug. An ABSENT
+  // health key (an older self-host build that doesn't send this field yet) is fine and falls through as
+  // healthy = null, exactly as before this field existed.
+  let healthy: number | null = null;
+  if (health !== undefined) {
+    if (typeof health !== "object" || health === null || typeof health.ok !== "boolean") {
+      return { error: "invalid_payload" };
+    }
+    healthy = health.ok ? 1 : 0;
+  }
+  // An empty batch is only valid when it's carrying a (well-formed) health-only ping (the hourly export
+  // still has to report health even in a tick with nothing new to export) -- a truly empty, health-less
+  // payload stays rejected exactly as before #4933.
   if (!instance_id || instance_id.length > MAX_INSTANCE_ID_CHARS || (events.length === 0 && healthy === null)) {
     return { error: "invalid_payload" };
   }
diff --git a/test/integration/orb-ingest.test.ts b/test/integration/orb-ingest.test.ts
index 2a5cf88d36..064323b3b9 100644
--- a/test/integration/orb-ingest.test.ts
+++ b/test/integration/orb-ingest.test.ts
@@ -181,13 +181,23 @@ describe("handleOrbIngest() health ping (#4933)", () => {
     expect((await instanceRow(db, "h2"))?.healthy).toBe(0);
   });
 
-  it("a malformed health object (not an object / ok not boolean) is treated as absent", async () => {
+  it("a malformed health object (not an object / ok not boolean) is rejected", async () => {
     const db = makeDb();
     expect(await handleOrbIngest(JSON.stringify({ instance_id: "h3", events: [], health: "bad" }), db)).toEqual({ error: "invalid_payload" });
     expect(await handleOrbIngest(JSON.stringify({ instance_id: "h4", events: [], health: { ok: "yes" } }), db)).toEqual({ error: "invalid_payload" });
     expect(await handleOrbIngest(JSON.stringify({ instance_id: "h5", events: [], health: null }), db)).toEqual({ error: "invalid_payload" });
   });
 
+  it("REGRESSION: a malformed health object is rejected even when real outcome events are ALSO present -- a present-but-invalid health key must never be silently dropped just because there's other work to do", async () => {
+    const db = makeDb();
+    const malformed = { instance_id: "h3b", events: [ev({ pr_hash: "h3b-p" })], health: { ok: "yes" } };
+    expect(await handleOrbIngest(JSON.stringify(malformed), db)).toEqual({ error: "invalid_payload" });
+    // Confirms the whole payload was rejected -- neither the event nor any instance row was persisted.
+    expect(await instanceRow(db, "h3b")).toBeNull();
+    const signalCount = await (db as unknown as TestD1Database).prepare("SELECT COUNT(*) AS n FROM orb_signals WHERE pr_hash='h3b-p'").first<{ n: number }>();
+    expect(signalCount?.n).toBe(0);
+  });
+
   it("an outcome-only ingest (no health field) never overwrites a previously-reported health status", async () => {
     const db = makeDb();
     await handleOrbIngest(JSON.stringify({ instance_id: "h6", events: [], health: { ok: true } }), db);