diff --git a/src/main/java/es/kauron/jstudy/controller/Controller.java b/src/main/java/es/kauron/jstudy/controller/Controller.java
index 4eb3edf..5796298 100644
--- a/src/main/java/es/kauron/jstudy/controller/Controller.java
+++ b/src/main/java/es/kauron/jstudy/controller/Controller.java
@@ -54,7 +54,7 @@ public class Controller implements Initializable {
     private MenuItem menuCloseTab, menuSave;
 
     private final BooleanProperty tabIsTable = new SimpleBooleanProperty(false);
-    private final Map<Tab, TableController> tabMap = new HashMap<>();
+    private final Map<Tab, Initializable> tabMap = new HashMap<>();
     private String updateURL, updateFileName;
     private Tab theTest = null;
 
@@ -67,9 +67,9 @@ public class Controller implements Initializable {
                 tabIsTable.set(tabMap.get(n) != null);
                 menuCloseTab.setDisable(!n.isClosable());
                 menuSave.disableProperty().unbind();
-                menuSave.setDisable(!tabMap.containsKey(n) || tabMap.get(n).saved.get());
-                if (tabMap.containsKey(n))
-                    menuSave.disableProperty().bind(tabMap.get(n).saved);
+                menuSave.setDisable(!isTableTab(n) || ((TableController) tabMap.get(n)).saved.get());
+                if (isTableTab(n))
+                    menuSave.disableProperty().bind(((TableController) tabMap.get(n)).saved);
             }
         });
         tabPane.getTabs().removeListener((ListChangeListener<Tab>) c -> theTest = null);
@@ -77,8 +77,10 @@ public class Controller implements Initializable {
             root.getScene().getWindow().setOnCloseRequest(event -> {
                 for (Tab tab : tabPane.getTabs()) {
                     EventHandler<Event> handler = tab.getOnCloseRequest();
-                    if (tabMap.containsKey(tab))
-                        tabMap.get(tab).stopTimer();
+                    if (isTableTab(tab))
+                        ((TableController) tabMap.get(tab)).stopTimer();
+                    else if (isTestTab(tab))
+                        ((TestController) tabMap.get(tab)).stopTimer();
                     if (tab.isClosable() && handler != null) {
                         tabPane.getSelectionModel().select(tab);
                         handler.handle(event);
@@ -90,6 +92,14 @@ public class Controller implements Initializable {
         new Thread(this::checkUpdate).start();
     }
 
+    private boolean isTableTab(Tab tab) {
+        return tabMap.containsKey(tab) && tabMap.get(tab) instanceof TableController;
+    }
+
+    private boolean isTestTab(Tab tab) {
+        return tabMap.containsKey(tab) && tabMap.get(tab) instanceof TestController;
+    }
+
     private void checkUpdate() {
         // Check new version via gitlab's REST API
         String newVersion;
@@ -227,9 +237,8 @@ public class Controller implements Initializable {
     @FXML
     private void onSaveAction(ActionEvent event) {
         Tab tab = tabPane.getSelectionModel().getSelectedItem();
-        if (tabMap.containsKey(tab)) {
-            tabMap.get(tab).onSaveAction(event);
-        }
+        if (isTableTab(tab))
+            ((TableController) tabMap.get(tab)).onSaveAction(event);
     }
 
     @FXML
@@ -277,9 +286,9 @@ public class Controller implements Initializable {
             MenuItem merge = new MenuItem("Merge with other table");
             merge.setOnAction(event -> {
                 Map<String, TableController> choices = new HashMap<>(tabMap.values().size() - 1);
-                for (TableController tc : tabMap.values())
-                    if (tc != loader.getController())
-                        choices.put(tc.getName(), tc);
+                for (Initializable tc : tabMap.values())
+                    if (tc instanceof TableController && tc != loader.getController())
+                        choices.put(((TableController) tc).getName(), ((TableController) tc));
 
                 ChoiceDialog<String> dialog = new ChoiceDialog<>();
                 dialog.setTitle("Merging tables...");
@@ -330,6 +339,7 @@ public class Controller implements Initializable {
             theTest = new Tab("Test: " + tabPane.getSelectionModel().getSelectedItem().getText(), root);
             tabPane.getTabs().add(theTest);
             tabPane.getSelectionModel().selectLast();
+            tabMap.put(theTest, loader.getController());
         } catch (IOException e) {
             e.printStackTrace();
         }
diff --git a/src/main/java/es/kauron/jstudy/controller/TestController.java b/src/main/java/es/kauron/jstudy/controller/TestController.java
index ce7526f..956df7b 100644
--- a/src/main/java/es/kauron/jstudy/controller/TestController.java
+++ b/src/main/java/es/kauron/jstudy/controller/TestController.java
@@ -129,5 +129,10 @@ public class TestController implements Initializable {
         item.set(ending);
         pauseCheckBox.setSelected(true);
         pauseCheckBox.setDisable(true);
+        clock.stop();
+    }
+
+    void stopTimer() {
+        clock.stop();
     }
 }
diff --git a/src/main/java/es/kauron/jstudy/util/Clock.java b/src/main/java/es/kauron/jstudy/util/Clock.java
index d4440df..6cd58e0 100644
--- a/src/main/java/es/kauron/jstudy/util/Clock.java
+++ b/src/main/java/es/kauron/jstudy/util/Clock.java
@@ -40,6 +40,11 @@ public class Clock {
         task = null;
     }
 
+    public void stop() {
+        timer.cancel();
+        timer.purge();
+    }
+
     private void setObservable() {
         time.set(String.format("%02d:%02d", seconds / SEC_TO_MIN, seconds % SEC_TO_MIN));
     }