diff --git a/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/BookGrid.java b/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/BookGrid.java
index 33e246b..0859c4e 100644
--- a/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/BookGrid.java
+++ b/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/BookGrid.java
@@ -268,7 +268,6 @@ public void setEdited(Product product) {
     @Override
     public void eventFired(Object event) {
         if (event instanceof BookEvent && isAttached()) {
-            logger.info("Book locking update");
             var bookEvent = (BookEvent) event;
             getUI().access(() -> {
                 ListDataProvider<Product> dataProvider = (ListDataProvider<Product>) getDataProvider();
diff --git a/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/BooksPresenter.java b/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/BooksPresenter.java
index 9d05b1c..cb3374b 100644
--- a/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/BooksPresenter.java
+++ b/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/BooksPresenter.java
@@ -153,6 +153,8 @@ public void editProduct(Product product) {
         if (product == null) {
             view.setFragmentParameter("");
             unlockBook();
+        } else if (product.getId() == -1) {
+            view.setFragmentParameter("new");
         } else {
             view.setFragmentParameter(product.getId() + "");
             lockBook(product.getId());
diff --git a/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/BooksView.java b/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/BooksView.java
index 403cfa6..64b28c5 100644
--- a/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/BooksView.java
+++ b/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/BooksView.java
@@ -130,9 +130,8 @@ private HorizontalLayout createTopBar() {
         ResetButtonForTextField.extend(filter);
         // Apply the filter to grid's data provider. TextField value is never
         // null
-        filter.addValueChangeListener(
-                event -> dataProvider
-                    .setFilter(book -> passesFilter(book, event.getValue())));
+        filter.addValueChangeListener(event -> dataProvider
+                .setFilter(book -> passesFilter(book, event.getValue())));
 
         newProduct = new Button(getTranslation(NEW_PRODUCT));
         newProduct.setId("new-product");
@@ -299,9 +298,11 @@ public void beforeLeave(ViewBeforeLeaveEvent event) {
             // IMHO: Navigator clears url too early and this workaround
             // shouldn't be necessary. This is a possible bug.
             var book = getSelectedRow();
-            getUI().access(() -> {
-                setFragmentParameter("" + book.getId());
-            });
+            if (book != null) {
+                getUI().access(() -> {
+                    setFragmentParameter("" + book.getId());
+                });
+            }
         } else {
             event.navigate();
         }
diff --git a/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/LockedBooksImpl.java b/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/LockedBooksImpl.java
index a2d8f0b..1d35a42 100644
--- a/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/LockedBooksImpl.java
+++ b/vaadincreate-ui/src/main/java/org/vaadin/tatu/vaadincreate/crud/LockedBooksImpl.java
@@ -34,12 +34,16 @@ public Collection<Integer> lockedBooks() {
 
     @Override
     public void lock(Integer id) {
+        if (id != null && id < 0) {
+            throw new IllegalArgumentException(
+                    "Id can't be null and must be positive");
+        }
         synchronized (books) {
             var match = books.keySet().stream().filter(i -> i.equals(id))
                     .findFirst();
             if (match.isPresent()) {
                 throw new IllegalStateException(
-                        "Can't open book already opened: " + id);
+                        "Can't locked book already locked: " + id);
             }
             books.put(id, null);
             eventBus.post(new BookEvent(id));
diff --git a/vaadincreate-ui/src/test/java/org/vaadin/tatu/vaadincreate/crud/BooksViewTest.java b/vaadincreate-ui/src/test/java/org/vaadin/tatu/vaadincreate/crud/BooksViewTest.java
index 1f3c876..5e25412 100644
--- a/vaadincreate-ui/src/test/java/org/vaadin/tatu/vaadincreate/crud/BooksViewTest.java
+++ b/vaadincreate-ui/src/test/java/org/vaadin/tatu/vaadincreate/crud/BooksViewTest.java
@@ -227,6 +227,16 @@ public void editProduct() {
         assertEquals("Edited book", edited.getProductName());
     }
 
+    @Test
+    public void editLockedProduct() {
+        var book = test(grid).item(0);
+        LockedBooks.get().lock(book.getId());
+
+        test(grid).click(1, 0);
+        assertFalse(form.isShown());
+        LockedBooks.get().unlock(book.getId());
+    }
+
     @Test
     public void editProductDiscardChanges() {
         test(grid).click(1, 0);