3 files changed, 12 insertions, 11 deletions
diff --git a/packages/connect/src/http_client.ts b/packages/connect/src/http_client.ts
index 924421f63..da052ba3c 100644
--- a/packages/connect/src/http_client.ts
+++ b/packages/connect/src/http_client.ts
@@ -112,12 +112,6 @@ export class HttpClient implements Client {
      */
     public async getFeesAsync(request: FeesRequest): Promise<FeesResponse> {
         assert.doesConformToSchema('request', request, schemas.relayerApiFeesPayloadSchema);
-        typeConverters.convertBigNumberFieldsToStrings(request, [
-            'makerTokenAmount',
-            'takerTokenAmount',
-            'expirationUnixTimestampSec',
-            'salt',
-        ]);
         const requestOpts = {
             payload: request,
         };
diff --git a/packages/connect/src/utils/type_converters.ts b/packages/connect/src/utils/type_converters.ts
index c136382fd..28810af1a 100644
--- a/packages/connect/src/utils/type_converters.ts
+++ b/packages/connect/src/utils/type_converters.ts
@@ -18,11 +18,6 @@ export const typeConverters = {
             'salt',
         ]);
     },
-    convertBigNumberFieldsToStrings(obj: object, fields: string[]): void {
-        _.each(fields, field => {
-            _.update(obj, field, (value: BigNumber) => value.toString());
-        });
-    },
     convertStringsFieldsToBigNumbers(obj: object, fields: string[]): void {
         _.each(fields, field => {
             _.update(obj, field, (value: string) => new BigNumber(value));
diff --git a/packages/connect/test/http_client_test.ts b/packages/connect/test/http_client_test.ts
index 21e7abb69..db7077531 100644
--- a/packages/connect/test/http_client_test.ts
+++ b/packages/connect/test/http_client_test.ts
@@ -124,6 +124,18 @@ describe('HttpClient', () => {
             const fees = await relayerClient.getFeesAsync(request);
             expect(fees).to.be.deep.equal(feesResponse);
         });
+        it('does not mutate input', async () => {
+            fetchMock.post(url, feesResponseJSON);
+            const makerTokenAmountBefore = new BigNumber(request.makerTokenAmount);
+            const takerTokenAmountBefore = new BigNumber(request.takerTokenAmount);
+            const saltBefore = new BigNumber(request.salt);
+            const expirationUnixTimestampSecBefore = new BigNumber(request.expirationUnixTimestampSec);
+            await relayerClient.getFeesAsync(request);
+            expect(makerTokenAmountBefore).to.be.deep.equal(request.makerTokenAmount);
+            expect(takerTokenAmountBefore).to.be.deep.equal(request.takerTokenAmount);
+            expect(saltBefore).to.be.deep.equal(request.salt);
+            expect(expirationUnixTimestampSecBefore).to.be.deep.equal(request.expirationUnixTimestampSec);
+        });
         it('throws an error for invalid JSON response', async () => {
             fetchMock.post(url, {test: 'dummy'});
             expect(relayerClient.getFeesAsync(request)).to.be.rejected();