2 files changed, 7 insertions, 2 deletions
diff --git a/packages/connect/src/utils/relayer_response_json_parsers.ts b/packages/connect/src/utils/relayer_response_json_parsers.ts
index 37099384f..2b2e1efe7 100644
--- a/packages/connect/src/utils/relayer_response_json_parsers.ts
+++ b/packages/connect/src/utils/relayer_response_json_parsers.ts
@@ -26,7 +26,7 @@ export const relayerResponseJsonParsers = {
     },
     parseAPIOrderJson(json: any): APIOrder {
         assert.doesConformToSchema('relayerApiOrder', json, schemas.relayerApiOrderSchema);
-        return typeConverters.convertOrderStringFieldsToBigNumber(json);
+        return typeConverters.convertAPIOrderStringFieldsToBigNumber(json);
     },
     parseOrderbookResponseJson(json: any): OrderbookResponse {
         assert.doesConformToSchema('orderBookResponse', json, schemas.relayerApiOrderbookResponseSchema);
diff --git a/packages/connect/src/utils/type_converters.ts b/packages/connect/src/utils/type_converters.ts
index c28cba0e1..4b211a0b2 100644
--- a/packages/connect/src/utils/type_converters.ts
+++ b/packages/connect/src/utils/type_converters.ts
@@ -36,7 +36,12 @@ export const typeConverters = {
     convertStringsFieldsToBigNumbers(obj: any, fields: string[]): any {
         const result = _.assign({}, obj);
         _.each(fields, field => {
-            _.update(result, field, (value: string) => new BigNumber(value));
+            _.update(result, field, (value: string) => {
+                if (_.isUndefined(value)) {
+                    throw new Error(`Could not find field '${field}' while converting string fields to BigNumber.`);
+                }
+                return new BigNumber(value);
+            });
         });
         return result;
     },