diff --git a/src/index.ts b/src/index.ts
index adf75a6..87e8225 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -169,6 +169,15 @@ server.registerTool(
     const { items: evidence } = ensureUniqueIds(evidenceItems, "evidence");
     const { items: claimItems } = ensureUniqueIds(claims.map((text) => ({ text })), "claim");
 
+    // Keep the internal no-source option distinct from caller-provided evidence
+    // ids. A real evidence item named "none" must remain selectable and must be
+    // returned as supporting_evidence rather than being mistaken for the sentinel.
+    const evidenceIds = new Set(evidence.map((item) => item.id));
+    let noEvidenceKey = "none";
+    for (let suffix = 1; evidenceIds.has(noEvidenceKey); suffix++) {
+      noEvidenceKey = `none_${suffix}`;
+    }
+
     const questions: Record<string, unknown> = {};
     for (const claim of claimItems) {
       questions[`relation_${claim.id}`] = choice(
@@ -181,7 +190,7 @@ server.registerTool(
       );
       if (evidence.length > 1) {
         const criteria: Record<string, string | null> = Object.fromEntries(evidence.map((e) => [e.id, null]));
-        criteria["none"] = "No single evidence item contains the content the claim depends on";
+        criteria[noEvidenceKey] = "No single evidence item contains the content the claim depends on";
         questions[`source_${claim.id}`] = choice(
           `Which evidence item does claim \`${claim.id}\` (${claim.text}) rest on?`,
           criteria,
@@ -202,8 +211,9 @@ server.registerTool(
       const validated = validateChoiceAnswer(relation, Object.keys(RELATION_TO_VERDICT));
       // source_* is optional auxiliary information, requested only for multiple
       // evidence items. Its absence does not invalidate the relation verdict,
-      // but a present source must name a supplied evidence id (or "none").
-      const sourceKeys = [...evidence.map((e) => e.id), "none"];
+      // but a present source must name a supplied evidence id or the internal
+      // no-evidence option.
+      const sourceKeys = [...evidence.map((e) => e.id), noEvidenceKey];
       const source = validateChoiceAnswer(answers[`source_${claim.id}`], sourceKeys);
       const valid = validated && Object.hasOwn(RELATION_TO_VERDICT, validated.choice) &&
         (relation.confidence == null || validated.confidence !== null);
@@ -231,7 +241,7 @@ server.registerTool(
         probabilities: relation.probabilities ?? null,
         confidence,
         action: confidence === null ? "review" : verifyAction(confidence, autoAccept),
-        supporting_evidence: source && source.choice !== "none" ? source.choice : null,
+        supporting_evidence: source && source.choice !== noEvidenceKey ? source.choice : null,
       };
     });
 
diff --git a/test/mock.test.mjs b/test/mock.test.mjs
index edcd592..6cba908 100644
--- a/test/mock.test.mjs
+++ b/test/mock.test.mjs
@@ -1566,6 +1566,35 @@ test("jev_verify still returns verified verdicts on a complete response", async
   });
 });
 
+test("jev_verify keeps a real evidence id named none distinct from its no-source option", async () => {
+  await withMock((request) => {
+    const criteria = request.questions.source_claim0.criteria;
+    assert.equal(criteria.none, null);
+    const noSourceKey = Object.entries(criteria).find(([, description]) =>
+      description === "No single evidence item contains the content the claim depends on"
+    )?.[0];
+    assert.ok(noSourceKey);
+    assert.notEqual(noSourceKey, "none");
+    return {
+      relation_claim0: pick("supports", Object.keys(request.questions.relation_claim0.criteria)),
+      source_claim0: pick("none", Object.keys(criteria)),
+    };
+  }, async (client) => {
+    const result = await client.callTool({
+      name: "jev_verify",
+      arguments: {
+        claims: ["The release is ready."],
+        evidence: [
+          { id: "none", text: "The release checks passed." },
+          { id: "notes", text: "Unrelated planning notes." },
+        ],
+      },
+    });
+    const body = payload(result);
+    assert.equal(body.results[0].supporting_evidence, "none");
+  });
+});
+
 test("TypeSafe package rejection invalidates only the malformed judgment without another paid request", async () => {
   await withMock(() => ({
     relation_claim0: pick("supports", ["supports", "contradicts", "says_nothing"]),