diff --git a/lib/ui/app/entity_dropdown.dart b/lib/ui/app/entity_dropdown.dart
index 24a8a1b29..957e59167 100644
--- a/lib/ui/app/entity_dropdown.dart
+++ b/lib/ui/app/entity_dropdown.dart
@@ -15,6 +15,7 @@ class EntityDropdown extends StatefulWidget {
     @required this.entityMap,
     @required this.onFilterChanged,
     @required this.onSelected,
+    this.validator,
     this.initialValue,
   });
 
@@ -25,6 +26,7 @@ class EntityDropdown extends StatefulWidget {
   final String initialValue;
   final Function(String) onFilterChanged;
   final Function(int) onSelected;
+  final Function validator;
 
   @override
   _EntityDropdownState createState() => _EntityDropdownState();
@@ -138,6 +140,7 @@ class _EntityDropdownState extends State<EntityDropdown> {
       onTap: () => _showOptions(),
       child: IgnorePointer(
         child: TextFormField(
+          validator: widget.validator,
           controller: _textController,
           decoration: InputDecoration(
             labelText: widget.labelText,
diff --git a/lib/ui/invoice/edit/invoice_edit_details.dart b/lib/ui/invoice/edit/invoice_edit_details.dart
index 0f027b395..61503fbed 100644
--- a/lib/ui/invoice/edit/invoice_edit_details.dart
+++ b/lib/ui/invoice/edit/invoice_edit_details.dart
@@ -20,7 +20,7 @@ class InvoiceEditDetails extends StatefulWidget {
   InvoiceEditDetailsState createState() => new InvoiceEditDetailsState();
 }
 
-class InvoiceEditDetailsState extends State<InvoiceEditDetails> {
+class InvoiceEditDetailsState extends State<InvoiceEditDetails> with AutomaticKeepAliveClientMixin {
   final _invoiceNumberController = TextEditingController();
   final _invoiceDateController = TextEditingController();
   final _poNumberController = TextEditingController();
@@ -29,6 +29,9 @@ class InvoiceEditDetailsState extends State<InvoiceEditDetails> {
 
   List _controllers = [];
 
+  @override
+  bool get wantKeepAlive => true;
+
   @override
   void didChangeDependencies() {
     _controllers = [
@@ -98,6 +101,9 @@ class InvoiceEditDetailsState extends State<InvoiceEditDetails> {
                         viewModel.clientMap[invoice.clientId]?.displayName,
                     entityList: viewModel.clientList,
                     entityMap: viewModel.clientMap,
+                    validator: (String val) => val.trim().isEmpty
+                        ? AppLocalization.of(context).pleaseSelectAClient
+                        : null,
                     onFilterChanged: viewModel.onEntityFilterChanged,
                     onSelected: (clientId) {
                       viewModel.onChanged(
diff --git a/lib/ui/invoice/edit/invoice_edit_items.dart b/lib/ui/invoice/edit/invoice_edit_items.dart
index 5560e8e42..691777729 100644
--- a/lib/ui/invoice/edit/invoice_edit_items.dart
+++ b/lib/ui/invoice/edit/invoice_edit_items.dart
@@ -58,7 +58,7 @@ class ItemEditDetails extends StatefulWidget {
   ItemEditDetailsState createState() => ItemEditDetailsState();
 }
 
-class ItemEditDetailsState extends State<ItemEditDetails> {
+class ItemEditDetailsState extends State<ItemEditDetails> with AutomaticKeepAliveClientMixin {
   final _productKeyController = TextEditingController();
   final _notesController = TextEditingController();
   final _costController = TextEditingController();
@@ -66,6 +66,9 @@ class ItemEditDetailsState extends State<ItemEditDetails> {
 
   var _controllers = [];
 
+  @override
+  bool get wantKeepAlive => true;
+
   @override
   void didChangeDependencies() {
     _controllers = [
diff --git a/lib/utils/localization.dart b/lib/utils/localization.dart
index 92ad0eaf2..525823431 100644
--- a/lib/utils/localization.dart
+++ b/lib/utils/localization.dart
@@ -143,6 +143,7 @@ class AppLocalization {
       'edit': 'Edit',
       'dismiss': 'Dismiss',
       'please_select_a_date': 'Please select a date',
+      'please_select_a_client': 'Please select a client',
 
       'payment': 'Payment',
       'payments': 'Payments',
@@ -296,6 +297,7 @@ class AppLocalization {
   String get edit => _localizedValues[locale.languageCode]['edit'];
   String get dismiss => _localizedValues[locale.languageCode]['dismiss'];
   String get pleaseSelectADate => _localizedValues[locale.languageCode]['please_select_a_date'];
+  String get pleaseSelectAClient => _localizedValues[locale.languageCode]['please_select_a_client'];
 
   String get payment => _localizedValues[locale.languageCode]['payment'];
   String get payments => _localizedValues[locale.languageCode]['payments'];