diff --git a/lib/exchange/changenow/changenow_exchange_provider.dart b/lib/exchange/changenow/changenow_exchange_provider.dart
index 20f529733..96b6142e6 100644
--- a/lib/exchange/changenow/changenow_exchange_provider.dart
+++ b/lib/exchange/changenow/changenow_exchange_provider.dart
@@ -114,7 +114,7 @@ class ChangeNowExchangeProvider extends ExchangeProvider {
 
     final uri = Uri.https(apiAuthority, createTradePath);
     final response = await post(uri, headers: headers, body: json.encode(body));
-    
+
     if (response.statusCode == 400) {
       final responseJSON = json.decode(response.body) as Map<String, dynamic>;
       final error = responseJSON['error'] as String;
@@ -130,7 +130,7 @@ class ChangeNowExchangeProvider extends ExchangeProvider {
     final id = responseJSON['id'] as String;
     final inputAddress = responseJSON['payinAddress'] as String;
     final refundAddress = responseJSON['refundAddress'] as String;
-    final extraId = responseJSON['payinExtraId'] as String;
+    final extraId = responseJSON['payinExtraId'] as String?;
 
     return Trade(
         id: id,
diff --git a/lib/view_model/exchange/exchange_view_model.dart b/lib/view_model/exchange/exchange_view_model.dart
index 68947d170..b19434166 100644
--- a/lib/view_model/exchange/exchange_view_model.dart
+++ b/lib/view_model/exchange/exchange_view_model.dart
@@ -307,12 +307,14 @@ abstract class ExchangeViewModelBase with Store {
   }
 
   Future<void> _calculateBestRate() async {
+    final amount = double.tryParse(isFixedRateMode ? receiveAmount : depositAmount) ?? 1;
+
     final result = await Future.wait<double>(
         _tradeAvailableProviders
             .map((element) => element.calculateAmount(
                 from: depositCurrency,
                 to: receiveCurrency,
-                amount: 1,
+                amount: amount,
                 isFixedRateMode: isFixedRateMode,
                 isReceiveAmount: false))
     );
@@ -322,7 +324,7 @@ abstract class ExchangeViewModelBase with Store {
     for (int i=0;i<result.length;i++) {
       if (result[i] != 0) {
         /// add this provider as its valid for this trade
-        _sortedAvailableProviders[result[i]] = _tradeAvailableProviders[i];
+        _sortedAvailableProviders[result[i] / amount] = _tradeAvailableProviders[i];
       }
     }
     if (_sortedAvailableProviders.isNotEmpty) {
@@ -345,7 +347,7 @@ abstract class ExchangeViewModelBase with Store {
         ? depositCurrency
         : receiveCurrency;
 
-    double lowestMin = double.maxFinite;
+    double? lowestMin = double.maxFinite;
     double? highestMax = 0.0;
 
     for (var provider in selectedProviders) {
@@ -360,8 +362,8 @@ abstract class ExchangeViewModelBase with Store {
             to: to,
             isFixedRateMode: isFixedRateMode);
 
-        if (tempLimits.min != null && tempLimits.min! < lowestMin) {
-          lowestMin = tempLimits.min!;
+        if (lowestMin != null && (tempLimits.min ?? -1) < lowestMin) {
+          lowestMin = tempLimits.min;
         }
         if (highestMax != null && (tempLimits.max ?? double.maxFinite) > highestMax) {
           highestMax = tempLimits.max;
@@ -371,7 +373,7 @@ abstract class ExchangeViewModelBase with Store {
       }
     }
 
-    if (lowestMin < double.maxFinite) {
+    if (lowestMin != double.maxFinite) {
       limits = Limits(min: lowestMin, max: highestMax);
 
       limitsState = LimitsLoadedSuccessfully(limits: limits);