diff --git a/packages/orderbook/src/seaport/fillable-units.spec.ts b/packages/orderbook/src/seaport/fillable-units.spec.ts
deleted file mode 100644
index 47c4bc4c7d..0000000000
--- a/packages/orderbook/src/seaport/fillable-units.spec.ts
+++ /dev/null
@@ -1,116 +0,0 @@
-import { expect } from 'chai';
-import { Fee, Order, ProtocolData } from '../openapi/sdk';
-import { determineFillableUnits } from './fillable-units';
-
-describe('determineFillableUnits', () => {
-  function createOrder(overrides?: Partial<Order>): Order {
-    // Default order object
-    const defaultOrder: Order = {
-      sell: [
-        {
-          type: 'ERC1155',
-          amount: '100',
-          contract_address: '0xEEb7Da6De152597830eD16361633e362A2F59410',
-          token_id: '123',
-        },
-      ],
-      buy: [
-        {
-          type: 'ERC20',
-          amount: '100',
-          contract_address: '0xFFb7Da6De152597830eD16361633e362A2F59411',
-        },
-      ],
-      type: Order.type.LISTING,
-      fill_status: {
-        numerator: '0',
-        denominator: '0',
-      },
-      account_address: '0x1237Da6De152597830eD16361633e362A2F59412',
-      fees: [
-        {
-          type: Fee.type.PROTOCOL,
-          amount: '100',
-          recipient_address: '0x4567Da6De152597830eD16361633e362A2F59413',
-        },
-      ],
-      chain: {
-        id: 'eip155:13473',
-        name: 'imtbl-zkevm-testnet',
-      },
-      created_at: '2024-06-18T06:16:57.902738Z',
-      end_at: '2026-06-18T06:16:14Z',
-      id: '019029fd-cf21-0a33-c77f-e121f5162f22',
-      order_hash: '0xba8ebe0b4ac6f1cc21a2274199b238959aaa0c59e1f2b31a8b7e8a66bf9f9635',
-      protocol_data: {
-        order_type: ProtocolData.order_type.PARTIAL_RESTRICTED,
-        counter: '0',
-        zone_address: '0x1004f9615e79462c711ff05a386bdba91a762822',
-        seaport_address: '0x7d117aa8bd6d31c4fa91722f246388f38ab19482',
-        seaport_version: '1.5',
-      },
-      salt: '0x3217c152146bf9f5',
-      signature: '0xf1522af4913159cdf1172d1c1bd511a3ca617f6c1d0b0ed588b2ce27618a2ac832c31ed4ee6ab2cea8af0efc2ad522468aa1c8c206291f4b343239acfea0a75e1b',
-      start_at: '2024-06-18T06:16:14Z',
-      status: {
-        name: 'ACTIVE',
-      },
-      updated_at: '2024-06-18T06:16:59.006679Z',
-    };
-
-    // Merge the overrides with the default order
-    return { ...defaultOrder, ...overrides };
-  }
-
-  it('should return the remaining fillable units for ERC1155 type when amountToFill is not provided', () => {
-    const orderInput = createOrder({
-      fill_status: {
-        numerator: '40',
-        denominator: '100',
-      },
-    });
-
-    const result = determineFillableUnits(orderInput);
-    expect(result).to.equal('60'); // (100 - 40) * 100 / 100
-  });
-
-  it('should return the original offer amount if order is unfilled i.e numerator or denominator is 0', () => {
-    const order: Order = createOrder();
-
-    const result = determineFillableUnits(order);
-    expect(result).to.equal('100');
-  });
-
-  it('should return amountToFill if provided', () => {
-    const order: Order = createOrder({
-      fill_status: {
-        numerator: '40',
-        denominator: '100',
-      },
-    });
-
-    const amountToFill = '50';
-    const result = determineFillableUnits(order, amountToFill);
-    expect(result).to.equal(amountToFill);
-  });
-
-  it('should return undefined if order type is not ERC1155', () => {
-    const order: Order = createOrder({
-      sell: [
-        {
-          type: 'ERC721',
-          contract_address: '0xEEb7Da6De152597830eD16361633e362A2F59410',
-          token_id: '123',
-        },
-      ],
-      fill_status: {
-        numerator: '0',
-        denominator: '0',
-      },
-    });
-
-    const result = determineFillableUnits(order);
-    // eslint-disable-next-line @typescript-eslint/no-unused-expressions
-    expect(result).to.be.undefined;
-  });
-});
diff --git a/packages/orderbook/src/seaport/fillable-units.ts b/packages/orderbook/src/seaport/fillable-units.ts
deleted file mode 100644
index 5cebba8a38..0000000000
--- a/packages/orderbook/src/seaport/fillable-units.ts
+++ /dev/null
@@ -1,22 +0,0 @@
-import { Order } from '../openapi/sdk';
-
-export function determineFillableUnits(order: Order, amountToFill?: string): string | undefined {
-  if (order.sell[0].type === 'ERC1155' && !amountToFill) {
-    // fill status is expressed as a ratio
-    const { numerator, denominator } = order.fill_status;
-    const originalOfferAmt = BigInt(order.sell[0].amount);
-
-    if (numerator === '0' || denominator === '0') {
-      return originalOfferAmt.toString();
-    }
-
-    // calculate the remaining amount to fill
-    // remaining = ((denominator - numerator) * originalOfferAmt) / denominator
-    const remaining = ((BigInt(denominator) - BigInt(numerator)) * BigInt(originalOfferAmt))
-        / BigInt(denominator);
-
-    return remaining.toString();
-  }
-
-  return amountToFill;
-}
diff --git a/packages/orderbook/src/seaport/seaport.ts b/packages/orderbook/src/seaport/seaport.ts
index d7983c2b1f..320572cb8b 100644
--- a/packages/orderbook/src/seaport/seaport.ts
+++ b/packages/orderbook/src/seaport/seaport.ts
@@ -36,7 +36,6 @@ import { getBulkOrderComponentsFromMessage, getOrderComponentsFromMessage } from
 import { SeaportLibFactory } from './seaport-lib-factory';
 import { prepareTransaction } from './transaction';
 import { mapImmutableOrderToSeaportOrderComponents } from './map-to-seaport-order';
-import { determineFillableUnits } from './fillable-units';
 
 export class Seaport {
   constructor(
@@ -176,7 +175,7 @@ export class Seaport {
             parameters: orderComponents,
             signature: order.signature,
           },
-          unitsToFill: determineFillableUnits(order, unitsToFill),
+          unitsToFill,
           extraData,
           tips,
         },
@@ -245,7 +244,7 @@ export class Seaport {
           parameters: orderComponents,
           signature: o.order.signature,
         },
-        unitsToFill: determineFillableUnits(o.order, o.unitsToFill),
+        unitsToFill: o.unitsToFill,
         extraData: o.extraData,
         tips,
       };