diff --git a/packages/order/src/order.test.ts b/packages/order/src/order.test.ts
index c71509a8..682c2d12 100644
--- a/packages/order/src/order.test.ts
+++ b/packages/order/src/order.test.ts
@@ -242,6 +242,7 @@ describe("OrderMatcher", () => {
           udtToCkb: { matchableCount: 1 },
         },
         candidates: {
+          bestGain: 0n,
           positiveGain: 0,
         },
       },
@@ -249,6 +250,55 @@ describe("OrderMatcher", () => {
     expect(match.diagnostics?.candidates.rejected.nonPositiveGain).toBeGreaterThan(0);
   });
 
+  it("does not select non-positive candidates after rejecting the empty allowance", () => {
+    const order = makeOrderCell({
+      ckbUnoccupied: ccc.fixedPointFrom(200),
+      udtValue: 0n,
+      info: Info.create(true, { ckbScale: 1n, udtScale: 1n }),
+      master: {
+        type: "absolute",
+        value: {
+          txHash: byte32FromByte("33"),
+          index: 1n,
+        },
+      },
+      outPoint: {
+        txHash: byte32FromByte("55"),
+        index: 0n,
+      },
+    });
+
+    const match = OrderManager.bestMatch(
+      [order],
+      {
+        ckbValue: -1n,
+        udtValue: ccc.fixedPointFrom(1000),
+      },
+      {
+        ckbScale: 1n,
+        udtScale: 1n,
+      },
+      {
+        feeRate: 0n,
+        ckbAllowanceStep: ccc.fixedPointFrom(1),
+      },
+    );
+
+    expect(match).toMatchObject({
+      ckbDelta: 0n,
+      udtDelta: 0n,
+      partials: [],
+      diagnostics: {
+        candidates: {
+          bestGain: 0n,
+          positiveGain: 0,
+        },
+      },
+    });
+    expect(match.diagnostics?.candidates.rejected.insufficientCkbAllowance).toBeGreaterThan(0);
+    expect(match.diagnostics?.candidates.rejected.nonPositiveGain).toBeGreaterThan(0);
+  });
+
   it("reports one primary allowance rejection reason per candidate", () => {
     const order = makeUdtToCkbOrder();
 
@@ -1734,8 +1784,8 @@ function exhaustiveSequentialBestMatch(
   const udtAllowanceStep = (
     options.ckbAllowanceStep * exchangeRate.ckbScale + exchangeRate.udtScale - 1n
   ) / exchangeRate.udtScale;
-  let best: Match | undefined;
-  let bestGain = -1n << 256n;
+  let best: Match = { ckbDelta: 0n, udtDelta: 0n, partials: [] };
+  let bestGain = 0n;
   for (const c2u of OrderManager.sequentialMatcher(
     orderPool,
     true,
@@ -1763,13 +1813,17 @@ function exhaustiveSequentialBestMatch(
       const udtAllowance = allowance.udtValue + udtDelta;
       const gain = (ckbDelta - ckbFee) * exchangeRate.ckbScale + udtDelta * exchangeRate.udtScale;
 
-      if (ckbAllowance >= 0n && udtAllowance >= 0n && gain > bestGain) {
+      if (
+        ckbAllowance >= 0n &&
+        udtAllowance >= 0n &&
+        gain > bestGain
+      ) {
         best = { ckbDelta, udtDelta, partials };
         bestGain = gain;
       }
     }
   }
-  return best ?? { ckbDelta: 0n, udtDelta: 0n, partials: [] };
+  return best;
 }
 
 function hasUniquePartialOrderOutPoints(partials: Match["partials"]): boolean {
diff --git a/packages/order/src/order.ts b/packages/order/src/order.ts
index 3b8c2e37..05e42995 100644
--- a/packages/order/src/order.ts
+++ b/packages/order/src/order.ts
@@ -387,22 +387,22 @@ export class OrderManager implements ScriptDeps {
     );
 
     let best = {
-      i: -1,
-      j: -1,
       ckbDelta: 0n,
       udtDelta: 0n,
       partials: [] as Match["partials"],
-      ckbAllowance: allowance.ckbValue,
-      udtAllowance: allowance.udtValue,
+      gain: 0n,
+    };
+    let advance = {
+      i: -1,
+      j: -1,
       gain: -1n << 256n,
     };
-    // best.i/best.j are offsets into the current two-entry frontiers; (0, 0)
+    // advance.i/advance.j are offsets into the current two-entry frontiers; (0, 0)
     // means the current frontier head is already optimal, so the search stops.
-    while (best.i !== 0 || best.j !== 0) {
-      ckb2UdtMatches.next(best.i);
-      udt2CkbMatches.next(best.j);
-      best.i = 0;
-      best.j = 0;
+    while (advance.i !== 0 || advance.j !== 0) {
+      ckb2UdtMatches.next(advance.i);
+      udt2CkbMatches.next(advance.j);
+      advance = { i: 0, j: 0, gain: -1n << 256n };
 
       for (const [i, c2u] of ckb2UdtMatches.buffer.entries()) {
         for (const [j, u2c] of udt2CkbMatches.buffer.entries()) {
@@ -431,23 +431,23 @@ export class OrderManager implements ScriptDeps {
             continue;
           }
           diagnostics.candidates.viable += 1;
+          if (gain > advance.gain) {
+            advance = { i, j, gain };
+          }
           if (partials.length > 0) {
             if (gain > 0n) {
               diagnostics.candidates.positiveGain += 1;
             } else {
               diagnostics.candidates.rejected.nonPositiveGain += 1;
+              continue;
             }
           }
 
           if (gain > best.gain) {
             best = {
-              i,
-              j,
               ckbDelta,
               udtDelta,
               partials,
-              ckbAllowance,
-              udtAllowance,
               gain,
             };
           }