2 files changed, 32 insertions, 0 deletions
diff --git a/packages/instant/src/index.umd.ts b/packages/instant/src/index.umd.ts
index 0acf3f2ad..0c2ce5ec1 100644
--- a/packages/instant/src/index.umd.ts
+++ b/packages/instant/src/index.umd.ts
@@ -19,6 +19,7 @@ import { analytics } from './util/analytics';
 import { assert } from './util/assert';
 import { providerFactory } from './util/provider_factory';
 import { util } from './util/util';
+import { coerceSignedOrderBigNumberOfString } from './util/signed_order_coercion'
 
 const isInstantRendered = (): boolean => !!document.getElementById(INJECTED_DIV_ID);
 
@@ -94,6 +95,12 @@ export interface ZeroExInstantConfig extends ZeroExInstantOverlayProps {
 
 export const render = (config: ZeroExInstantConfig, selector: string = DEFAULT_ZERO_EX_CONTAINER_SELECTOR) => {
     validateInstantRenderConfig(config, selector);
+
+    // TODO(David Sun) test functionality of order bignumber version coercion
+    if (!_.isString(config.orderSource)) {
+        config.orderSource = config.orderSource.map(coerceSignedOrderBigNumberOfString);
+    }
+
     if (config.shouldDisablePushToHistory) {
         if (!isInstantRendered()) {
             renderInstant(config, selector);
diff --git a/packages/instant/src/util/signed_order_coercion.ts b/packages/instant/src/util/signed_order_coercion.ts
new file mode 100644
index 000000000..649596a3d
--- /dev/null
+++ b/packages/instant/src/util/signed_order_coercion.ts
@@ -0,0 +1,25 @@
+import { BigNumber } from '@0x/asset-buyer';
+import { SignedOrder } from '@0x/types';
+
+export const coerceBigNumberOrString = (value: any): BigNumber => {
+    if (typeof value === 'string') {
+        return new BigNumber(value);
+    }
+    if (BigNumber.isBigNumber(value)) {
+        return new BigNumber(value.toString());
+    }
+    return value;
+};
+
+// function implies that the signed order already has been invalidated
+export const coerceSignedOrderBigNumberOfString = (order: SignedOrder): SignedOrder => {
+    return {
+        ...order,
+        makerFee: coerceBigNumberOrString(order.makerFee),
+        takerFee: coerceBigNumberOrString(order.takerFee),
+        makerAssetAmount: coerceBigNumberOrString(order.makerAssetAmount),
+        takerAssetAmount: coerceBigNumberOrString(order.takerAssetAmount),
+        salt: coerceBigNumberOrString(order.salt),
+        expirationTimeSeconds: coerceBigNumberOrString(order.expirationTimeSeconds),
+    };
+};