diff --git a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/JavaFxApp.java b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/JavaFxApp.java
index 32a4345c..8ced575b 100644
--- a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/JavaFxApp.java
+++ b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/JavaFxApp.java
@@ -293,7 +293,7 @@ private InterruptionDetectedDecision showAutomaticInterruptionDialog(final Local
             LOG.info("Showing automatic interruption alert starting at {} for {}...", startOfInterruption,
                     interruption);
             final Optional<ButtonType> selectedButton = alert.showAndWait();
-            final InterruptionDetectedDecision decision = evaluateButton(selectedButton);
+            final InterruptionDetectedDecision decision = evaluateButton(selectedButton.orElse(null));
             LOG.info("User clicked button {} -> {}", selectedButton, decision);
             return decision;
         }
@@ -313,26 +313,23 @@ private Alert createAlertDialog(final LocalTime startOfInterruption, final Durat
             return alert;
         }
 
-        private InterruptionDetectedDecision evaluateButton(final Optional<ButtonType> selectedButton)
+        private InterruptionDetectedDecision evaluateButton(final ButtonType selectedButton)
         {
-            if (isButton(selectedButton, ButtonData.FINISH) && !state.stoppedWorkingForToday.get())
+            if (selectedButton == null)
+            {
+                return InterruptionDetectedDecision.SKIP_INTERRUPTION;
+            }
+            if (selectedButton.getButtonData() == ButtonData.FINISH && !state.stoppedWorkingForToday.get())
             {
                 return InterruptionDetectedDecision.STOP_WORKING_FOR_TODAY;
             }
-            if (isButton(selectedButton, ButtonData.YES))
+            if (selectedButton.getButtonData() == ButtonData.YES)
             {
                 return InterruptionDetectedDecision.ADD_INTERRUPTION;
             }
             return InterruptionDetectedDecision.SKIP_INTERRUPTION;
         }
 
-        private boolean isButton(final Optional<ButtonType> button, final ButtonData data)
-        {
-            return button.map(ButtonType::getButtonData)
-                    .filter(d -> d == data)
-                    .isPresent();
-        }
-
         @Override
         public void recordUpdated(final DayRecord day)
         {
diff --git a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/feature/InterruptionPresetFeature.java b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/feature/InterruptionPresetFeature.java
index 17f2df89..e58e8163 100644
--- a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/feature/InterruptionPresetFeature.java
+++ b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/feature/InterruptionPresetFeature.java
@@ -4,6 +4,7 @@
 import java.text.ParsePosition;
 import java.time.Duration;
 import java.util.List;
+import java.util.Locale;
 import java.util.function.UnaryOperator;
 
 import org.itsallcode.whiterabbit.logic.service.AppService;
@@ -65,7 +66,7 @@ private MenuItem createMenuitem(final Duration interruption)
         final String verb = interruption.isNegative() ? "Subtract" : "Add";
         final MenuItem menuItem = new MenuItem(
                 verb + " interruption of " + appService.formatter().format(interruption.abs()));
-        menuItem.setId(verb.toLowerCase() + "-interruption-preset-" + interruption.toString());
+        menuItem.setId(verb.toLowerCase(Locale.ENGLISH) + "-interruption-preset-" + interruption.toString());
         menuItem.setOnAction(event -> addInterruptionForToday(interruption));
         return menuItem;
     }
@@ -83,7 +84,6 @@ private static class DurationInputDialog extends Dialog<Duration>
 
         private DurationInputDialog()
         {
-            final DialogPane dialogPane = getDialogPane();
             final int maxValue = (int) Duration.ofHours(8).toMinutes();
 
             spinner = new Spinner<>(0, maxValue, 0, 5);
@@ -117,6 +117,7 @@ private DurationInputDialog()
             GridPane.setHgrow(spinner, Priority.ALWAYS);
             GridPane.setFillWidth(spinner, true);
 
+            final DialogPane dialogPane = getDialogPane();
             label = createContentLabel(dialogPane.getContentText());
             label.setPrefWidth(Region.USE_COMPUTED_SIZE);
             label.textProperty().bind(dialogPane.contentTextProperty());
diff --git a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/table/days/DayRecordTable.java b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/table/days/DayRecordTable.java
index 67f70754..d7c9ace7 100644
--- a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/table/days/DayRecordTable.java
+++ b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/table/days/DayRecordTable.java
@@ -103,14 +103,11 @@ private void updateRows(final List<DayRecord> sortedDays)
 
     private void updateSelectedRow(final MonthIndex previousMonth, final MonthIndex month)
     {
-        final boolean isCurrentMonth = month.getYearMonth().equals(clockService.getCurrentYearMonth());
-        final boolean otherMonthSelected = previousMonth != null
-                && !month.getYearMonth().equals(previousMonth.getYearMonth());
-        if (!otherMonthSelected)
+        if (!otherMonthSelected(previousMonth, month))
         {
             return;
         }
-        if (isCurrentMonth)
+        if (isCurrentMonth(month))
         {
             selectRow(clockService.getCurrentDate());
         }
@@ -120,6 +117,17 @@ private void updateSelectedRow(final MonthIndex previousMonth, final MonthIndex
         }
     }
 
+    private boolean otherMonthSelected(final MonthIndex previousMonth, final MonthIndex month)
+    {
+        return previousMonth != null
+                && !month.getYearMonth().equals(previousMonth.getYearMonth());
+    }
+
+    private boolean isCurrentMonth(final MonthIndex month)
+    {
+        return month.getYearMonth().equals(clockService.getCurrentYearMonth());
+    }
+
     @SuppressWarnings("java:S110") // Deep inheritance tree required by JavaFx
     public TableView<DayRecordPropertyAdapter> initTable()
     {
diff --git a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/DailyProjectReportViewer.java b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/DailyProjectReportViewer.java
index 0b150589..57a2fa1c 100644
--- a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/DailyProjectReportViewer.java
+++ b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/DailyProjectReportViewer.java
@@ -103,7 +103,7 @@ private TreeTableView<ReportRow> createTreeTable()
         final TreeItem<ReportRow> root = new TreeItem<>();
 
         root.getChildren().addAll(report.getDays().stream()
-                .map(this::createDayTreeItem)
+                .map(DailyProjectReportViewer::createDayTreeItem)
                 .toList());
 
         final TreeTableView<ReportRow> treeTable = new TreeTableView<>(root);
@@ -125,7 +125,7 @@ private TreeTableView<ReportRow> createTreeTable()
         return treeTable;
     }
 
-    private TreeItem<ReportRow> createDayTreeItem(final ProjectReportDay day)
+    private static TreeItem<ReportRow> createDayTreeItem(final ProjectReportDay day)
     {
         final TreeItem<ReportRow> treeItem = new TreeItem<>(new ReportRow(day));
         treeItem.setExpanded(true);
diff --git a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/MenuBarBuilder.java b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/MenuBarBuilder.java
index 9774befb..211f273a 100644
--- a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/MenuBarBuilder.java
+++ b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/MenuBarBuilder.java
@@ -68,12 +68,12 @@ public MenuBar build()
         return menuBar;
     }
 
-    private SeparatorMenuItem separatorItem()
+    private static SeparatorMenuItem separatorItem()
     {
         return new SeparatorMenuItem();
     }
 
-    private Menu menu(final String label, final String id)
+    private static Menu menu(final String label, final String id)
     {
         final Menu menu = new Menu(label);
         menu.setId(id);
@@ -91,12 +91,12 @@ private MenuItem createStopWorkingForTodayMenuItem()
         return menuItem;
     }
 
-    private MenuItem menuItem(final String label, final String id, final Runnable action)
+    private static MenuItem menuItem(final String label, final String id, final Runnable action)
     {
         return menuItem(label, id, event -> action.run());
     }
 
-    private MenuItem menuItem(final String label, final String id, final EventHandler<ActionEvent> action)
+    private static MenuItem menuItem(final String label, final String id, final EventHandler<ActionEvent> action)
     {
         final MenuItem menuItem = new MenuItem(label);
         menuItem.setId(id);
diff --git a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/PluginManagerViewer.java b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/PluginManagerViewer.java
index de5e5346..52fa0ce0 100644
--- a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/PluginManagerViewer.java
+++ b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/PluginManagerViewer.java
@@ -64,11 +64,11 @@ private TableView<PluginTableEntry> createTableView()
     private List<PluginTableEntry> getAllPlugins()
     {
         return pluginManager.getAllPlugins().stream()
-                .map(this::createTableEntry)
+                .map(PluginManagerViewer::createTableEntry)
                 .toList();
     }
 
-    private PluginTableEntry createTableEntry(final AppPlugin plugin)
+    private static PluginTableEntry createTableEntry(final AppPlugin plugin)
     {
         return new PluginTableEntry(plugin);
     }
diff --git a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/YearlyProjectReportViewer.java b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/YearlyProjectReportViewer.java
index df0e827e..70369595 100644
--- a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/YearlyProjectReportViewer.java
+++ b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/YearlyProjectReportViewer.java
@@ -66,7 +66,7 @@ private TableView<ReportRow> createTreeTable()
         return treeTable;
     }
 
-    private ReportRow createRow(final int year, final ProjectReportActivity project)
+    private static ReportRow createRow(final int year, final ProjectReportActivity project)
     {
         return new ReportRow(year, project);
     }
diff --git a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/widget/AutoCompleteTextField.java b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/widget/AutoCompleteTextField.java
index 6b27728a..a5fb7b08 100644
--- a/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/widget/AutoCompleteTextField.java
+++ b/jfxui/src/main/java/org/itsallcode/whiterabbit/jfxui/ui/widget/AutoCompleteTextField.java
@@ -87,7 +87,7 @@ private MenuItem createMenuItem(final AutocompleteProposal result)
         return item;
     }
 
-    private List<Text> highlightMatch(final AutocompleteProposal result)
+    private static List<Text> highlightMatch(final AutocompleteProposal result)
     {
         final int matchPositionStart = result.getMatchPositionStart();
         final List<Text> textParts = new ArrayList<>();
diff --git a/jfxui/src/uiTest/java/org/itsallcode/whiterabbit/jfxui/JavaFxAppUiTestBase.java b/jfxui/src/uiTest/java/org/itsallcode/whiterabbit/jfxui/JavaFxAppUiTestBase.java
index 46cca8fd..2e6ee675 100644
--- a/jfxui/src/uiTest/java/org/itsallcode/whiterabbit/jfxui/JavaFxAppUiTestBase.java
+++ b/jfxui/src/uiTest/java/org/itsallcode/whiterabbit/jfxui/JavaFxAppUiTestBase.java
@@ -92,7 +92,7 @@ public void setCommandLineArgs(final List<String> commandLineArgs)
 
     protected void doStart(final Stage stage, final ProjectConfig projectConfig)
     {
-        LOG.info("Starting application using stage {}", stage);
+        LOG.debug("Starting application using stage {}", stage);
 
         timeUtil = TimeUtil.start(initialTime);
         final TestDirProvider testDirProvider = TestDirProvider.create(tempDir);
@@ -107,14 +107,14 @@ protected void doStart(final Stage stage, final ProjectConfig projectConfig)
         this.javaFxApp.start(stage);
 
         timeUtil.captureScheduledRunnables();
-        LOG.info("Application startup finished");
+        LOG.debug("Application startup finished");
     }
 
     protected void doStop()
     {
-        LOG.info("Preparing application shutdown");
+        LOG.debug("Preparing application shutdown");
         this.javaFxApp.prepareShutdown();
-        LOG.info("Application shutdown done");
+        LOG.debug("Application shutdown done");
     }
 
     private void prepareConfiguration(final ProjectConfig projectConfig, final WorkingDirProvider testDirProvider)
diff --git a/logic/src/main/java/org/itsallcode/whiterabbit/logic/autocomplete/AutocompleteService.java b/logic/src/main/java/org/itsallcode/whiterabbit/logic/autocomplete/AutocompleteService.java
index 995d89b7..049fa452 100644
--- a/logic/src/main/java/org/itsallcode/whiterabbit/logic/autocomplete/AutocompleteService.java
+++ b/logic/src/main/java/org/itsallcode/whiterabbit/logic/autocomplete/AutocompleteService.java
@@ -1,11 +1,13 @@
 package org.itsallcode.whiterabbit.logic.autocomplete;
 
 import static java.util.function.Function.identity;
-import static java.util.stream.Collectors.*;
+import static java.util.stream.Collectors.counting;
+import static java.util.stream.Collectors.groupingBy;
 
 import java.time.LocalDate;
 import java.time.Period;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
@@ -30,15 +32,16 @@ public class AutocompleteService
     private final CachingStorage storage;
     private final ClockService clockService;
 
-    private final CachingAutocompleter dayCommentAutocompleter = new CachingAutocompleter(this::getDayComments);
-    private final CachingAutocompleter activityCommentAutocompleter = new CachingAutocompleter(
-            this::getActivityComments);
+    private final CachingAutocompleter dayCommentAutocompleter;
+    private final CachingAutocompleter activityCommentAutocompleter;
 
-    public AutocompleteService(final CachingStorage storage, final ClockService clockService)
+    public AutocompleteService(final CachingStorage storage, final ClockService clockService, final Locale locale)
     {
-        this.storage = storage;
         this.clockService = clockService;
-        storage.addCacheInvalidationListener(this::invalidateCache);
+        this.dayCommentAutocompleter = new CachingAutocompleter(this::getDayComments, locale);
+        this.activityCommentAutocompleter = new CachingAutocompleter(this::getActivityComments, locale);
+        this.storage = storage;
+        this.storage.addCacheInvalidationListener(this::invalidateCache);
     }
 
     private void invalidateCache(final MonthIndex updatedMonth)
@@ -108,14 +111,16 @@ public Optional<ProjectImpl> getSuggestedProject()
         return mostFrequentlyUsedProject;
     }
 
-    private class CachingAutocompleter implements AutocompleteEntrySupplier
+    private static class CachingAutocompleter implements AutocompleteEntrySupplier
     {
         private TextIndex index;
         private final Supplier<List<String>> availableTextSupplier;
+        private final Locale locale;
 
-        private CachingAutocompleter(final Supplier<List<String>> availableTextSupplier)
+        private CachingAutocompleter(final Supplier<List<String>> availableTextSupplier, final Locale locale)
         {
             this.availableTextSupplier = availableTextSupplier;
+            this.locale = locale;
         }
 
         private void invalidateCache()
@@ -128,7 +133,7 @@ public List<AutocompleteProposal> getEntries(final String prompt)
         {
             if (index == null)
             {
-                index = TextIndex.build(availableTextSupplier.get());
+                index = TextIndex.build(availableTextSupplier.get(), locale);
             }
             return index.getEntries(prompt);
         }
diff --git a/logic/src/main/java/org/itsallcode/whiterabbit/logic/autocomplete/TextIndex.java b/logic/src/main/java/org/itsallcode/whiterabbit/logic/autocomplete/TextIndex.java
index b174a7f8..e7afaa86 100644
--- a/logic/src/main/java/org/itsallcode/whiterabbit/logic/autocomplete/TextIndex.java
+++ b/logic/src/main/java/org/itsallcode/whiterabbit/logic/autocomplete/TextIndex.java
@@ -5,7 +5,9 @@
 import static java.util.stream.Collectors.groupingBy;
 
 import java.util.Collection;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.SortedSet;
 import java.util.TreeSet;
@@ -21,28 +23,35 @@ class TextIndex implements AutocompleteEntrySupplier
     private final Map<String, List<String>> lowerCaseIndex;
     private final SortedSet<String> lowerCaseValues;
     private final Map<String, Long> lowerCaseFrequency;
+    private final Locale locale;
 
     private TextIndex(final Map<String, List<String>> lowerCaseIndex, final SortedSet<String> lowerCaseValues,
-            final Map<String, Long> lowerCaseFrequency)
+            final Map<String, Long> lowerCaseFrequency, final Locale locale)
     {
-        this.lowerCaseIndex = lowerCaseIndex;
-        this.lowerCaseValues = lowerCaseValues;
-        this.lowerCaseFrequency = lowerCaseFrequency;
+        this.lowerCaseIndex = new HashMap<>(lowerCaseIndex);
+        this.lowerCaseValues = new TreeSet<>(lowerCaseValues);
+        this.lowerCaseFrequency = new HashMap<>(lowerCaseFrequency);
+        this.locale = locale;
     }
 
-    static TextIndex build(final Collection<String> entries)
+    static TextIndex build(final Collection<String> entries, final Locale locale)
     {
         final List<String> uniqueEntries = entries.stream().distinct().toList();
 
         final Map<String, List<String>> lowerCaseIndex = uniqueEntries.stream()
-                .collect(groupingBy(String::toLowerCase));
+                .collect(groupingBy(value -> value.toLowerCase(locale)));
         final SortedSet<String> lowerCaseValues = new TreeSet<>(lowerCaseIndex.keySet());
-        final Map<String, Long> lowerCaseFrequency = entries.stream().map(String::toLowerCase)
+        final Map<String, Long> lowerCaseFrequency = entries.stream().map(value -> value.toLowerCase(locale))
                 .collect(groupingBy(identity(), counting()));
         LOG.trace("Creating autocompleter for {} entries ({} unique): {}, frequencies: {}", entries.size(),
                 uniqueEntries.size(),
                 uniqueEntries, lowerCaseFrequency);
-        return new TextIndex(lowerCaseIndex, lowerCaseValues, lowerCaseFrequency);
+        return new TextIndex(lowerCaseIndex, lowerCaseValues, lowerCaseFrequency, locale);
+    }
+
+    private String toLowerCase(final String value)
+    {
+        return value.toLowerCase(locale);
     }
 
     @Override
@@ -56,8 +65,8 @@ public List<AutocompleteProposal> getEntries(final String searchText)
         {
             return createProposals(lowerCaseValues, searchText);
         }
-        final SortedSet<String> lowerCaseMatches = lowerCaseValues.subSet(searchText.toLowerCase(),
-                searchText.toLowerCase() + Character.MAX_VALUE);
+        final SortedSet<String> lowerCaseMatches = lowerCaseValues.subSet(toLowerCase(searchText),
+                toLowerCase(searchText) + Character.MAX_VALUE);
         return createProposals(lowerCaseMatches, searchText);
     }
 
@@ -75,8 +84,8 @@ private List<AutocompleteProposal> createProposals(final SortedSet<String> lower
 
     private AutocompleteProposal createProposal(final String searchText, final String proposedText)
     {
-        final int matchPositionStart = proposedText.toLowerCase().indexOf(searchText.toLowerCase());
-        final long priority = lowerCaseFrequency.getOrDefault(proposedText.toLowerCase(), 0L);
+        final int matchPositionStart = toLowerCase(proposedText).indexOf(toLowerCase(searchText));
+        final long priority = lowerCaseFrequency.getOrDefault(toLowerCase(proposedText), 0L);
         LOG.trace("Create proposal for '{}'. Proposal: {}, priority: {}", searchText, proposedText, priority);
         return new AutocompleteProposal(proposedText, priority, matchPositionStart, searchText.length());
     }
diff --git a/logic/src/main/java/org/itsallcode/whiterabbit/logic/model/MonthIndex.java b/logic/src/main/java/org/itsallcode/whiterabbit/logic/model/MonthIndex.java
index 641da110..fc23f216 100644
--- a/logic/src/main/java/org/itsallcode/whiterabbit/logic/model/MonthIndex.java
+++ b/logic/src/main/java/org/itsallcode/whiterabbit/logic/model/MonthIndex.java
@@ -27,15 +27,16 @@ public class MonthIndex
     private final MonthData monthRecord;
     private final Map<LocalDate, DayRecord> days;
 
-    private MonthIndex(ModelFactory modelFactory, MonthData monthRecord, Map<LocalDate, DayRecord> days)
+    private MonthIndex(final ModelFactory modelFactory, final MonthData monthRecord,
+            final Map<LocalDate, DayRecord> days)
     {
         this.modelFactory = Objects.requireNonNull(modelFactory, "modelFactory");
         this.monthRecord = monthRecord;
         this.days = days;
     }
 
-    public static MonthIndex create(ContractTermsService contractTerms, ProjectService projectService,
-            ModelFactory modelFactory, MonthData monthRecord)
+    public static MonthIndex create(final ContractTermsService contractTerms, final ProjectService projectService,
+            final ModelFactory modelFactory, final MonthData monthRecord)
     {
         final Map<LocalDate, DayData> jsonDays = monthRecord.getDays().stream()
                 .collect(toMap(DayData::getDate, Function.identity()));
@@ -58,7 +59,8 @@ public static MonthIndex create(ContractTermsService contractTerms, ProjectServi
         return monthIndex;
     }
 
-    private static DayData createDummyDay(LocalDate date, ContractTermsService contractTerms, ModelFactory modelFactory)
+    private static DayData createDummyDay(final LocalDate date, final ContractTermsService contractTerms,
+            final ModelFactory modelFactory)
     {
         final DayData day = modelFactory.createDayData();
         day.setDate(date);
@@ -75,12 +77,12 @@ public YearMonth getYearMonth()
         return YearMonth.of(monthRecord.getYear(), monthRecord.getMonth());
     }
 
-    public DayRecord getDay(LocalDate date)
+    public DayRecord getDay(final LocalDate date)
     {
         return days.get(date);
     }
 
-    public void put(DayRecord day)
+    public void put(final DayRecord day)
     {
         this.days.put(day.getDate(), day);
     }
@@ -111,7 +113,7 @@ public Stream<DayRecord> getSortedDays()
                 .sorted(Comparator.comparing(DayRecord::getDate));
     }
 
-    public void setOvertimePreviousMonth(Duration overtimePreviousMonth)
+    public void setOvertimePreviousMonth(final Duration overtimePreviousMonth)
     {
         monthRecord.setOvertimePreviousMonth(overtimePreviousMonth);
     }
diff --git a/logic/src/main/java/org/itsallcode/whiterabbit/logic/report/project/ProjectReportGenerator.java b/logic/src/main/java/org/itsallcode/whiterabbit/logic/report/project/ProjectReportGenerator.java
index 74a8d063..2a09947e 100644
--- a/logic/src/main/java/org/itsallcode/whiterabbit/logic/report/project/ProjectReportGenerator.java
+++ b/logic/src/main/java/org/itsallcode/whiterabbit/logic/report/project/ProjectReportGenerator.java
@@ -40,7 +40,7 @@ public ProjectReport generateReport(final YearMonth month)
                                 .filter(activity -> activity.getProject() != null)
                                 .collect(groupingBy(Activity::getProject))
                                 .values().stream()
-                                .map(this::aggregateProject)
+                                .map(ProjectReportGenerator::aggregateProject)
                                 .toList();
 
                 return new ProjectReportImpl(month, reportDays, reportProjects);
@@ -53,7 +53,7 @@ private ProjectReportDay generateDayReport(final DayRecord dayRecord)
                                 .filter(activity -> activity.getProject() != null)
                                 .collect(groupingBy(this::activityProject))
                                 .values().stream()
-                                .map(this::aggregateProject)
+                                .map(ProjectReportGenerator::aggregateProject)
                                 .toList();
 
                 return new DayImpl(dayRecord.getDate(), dayRecord.getType(), dayRecord.getComment(), projects);
@@ -64,7 +64,7 @@ private String activityProject(final Activity activity)
                 return activity.getProject().getProjectId();
         }
 
-        private ProjectReportActivity aggregateProject(final List<Activity> projectActivites)
+        private static ProjectReportActivity aggregateProject(final List<Activity> projectActivites)
         {
                 final Duration totalWorkingTime = projectActivites.stream()
                                 .filter(activity -> activity.getDuration() != null)
diff --git a/logic/src/main/java/org/itsallcode/whiterabbit/logic/service/AppService.java b/logic/src/main/java/org/itsallcode/whiterabbit/logic/service/AppService.java
index 53a8ab89..561a30a7 100644
--- a/logic/src/main/java/org/itsallcode/whiterabbit/logic/service/AppService.java
+++ b/logic/src/main/java/org/itsallcode/whiterabbit/logic/service/AppService.java
@@ -109,7 +109,8 @@ public static AppService create(final Config config, final Clock clock,
                 projectService, holidayService);
 
         final ClockService clockService = new ClockService(clock);
-        final AutocompleteService autocompleteService = new AutocompleteService(storage, clockService);
+        final AutocompleteService autocompleteService = new AutocompleteService(storage, clockService,
+                config.getLocale());
         final SchedulingService schedulingService = new SchedulingService(clockService, scheduledExecutor);
         final DelegatingAppServiceCallback appServiceCallback = new DelegatingAppServiceCallback();
         final WorkingTimeService workingTimeService = new WorkingTimeService(storage, clockService, appServiceCallback);
diff --git a/logic/src/main/java/org/itsallcode/whiterabbit/logic/service/plugin/AppPluginImpl.java b/logic/src/main/java/org/itsallcode/whiterabbit/logic/service/plugin/AppPluginImpl.java
index eb38ce11..9483a5e4 100644
--- a/logic/src/main/java/org/itsallcode/whiterabbit/logic/service/plugin/AppPluginImpl.java
+++ b/logic/src/main/java/org/itsallcode/whiterabbit/logic/service/plugin/AppPluginImpl.java
@@ -20,14 +20,14 @@ class AppPluginImpl implements AppPlugin
     private final Plugin plugin;
     private final Config config;
 
-    private AppPluginImpl(Config config, AppPluginOrigin origin, Plugin plugin)
+    private AppPluginImpl(final Config config, final AppPluginOrigin origin, final Plugin plugin)
     {
         this.config = config;
         this.origin = origin;
         this.plugin = plugin;
     }
 
-    public static AppPluginImpl create(Config config, AppPluginOrigin origin, Plugin plugin)
+    public static AppPluginImpl create(final Config config, final AppPluginOrigin origin, final Plugin plugin)
     {
         return new AppPluginImpl(config, origin, plugin);
     }
@@ -57,20 +57,20 @@ public AppPluginOrigin getOrigin()
         return origin;
     }
 
-    public boolean supports(Class<? extends PluginFeature> featureType)
+    public boolean supports(final Class<? extends PluginFeature> featureType)
     {
         try
         {
             return plugin.supports(featureType);
         }
-        catch (final Exception e)
+        catch (final RuntimeException e)
         {
             LOG.warn("Error loading plugin '{}'", getId(), e);
             return false;
         }
     }
 
-    public <T extends PluginFeature> Optional<T> getFeature(Class<T> featureType)
+    public <T extends PluginFeature> Optional<T> getFeature(final Class<T> featureType)
     {
         return plugin.getFeature(featureType);
     }
@@ -93,19 +93,19 @@ public String toString()
 
     private class PluginConfigImpl implements PluginConfiguration
     {
-        private String prefixed(String key)
+        private String prefixed(final String key)
         {
             return plugin.getId() + "." + key;
         }
 
         @Override
-        public String getMandatoryValue(String key)
+        public String getMandatoryValue(final String key)
         {
             return config.getMandatoryValue(prefixed(key));
         }
 
         @Override
-        public Optional<String> getOptionalValue(String key)
+        public Optional<String> getOptionalValue(final String key)
         {
             return config.getOptionalValue(prefixed(key));
         }
diff --git a/logic/src/main/java/org/itsallcode/whiterabbit/logic/service/plugin/PluginRegistry.java b/logic/src/main/java/org/itsallcode/whiterabbit/logic/service/plugin/PluginRegistry.java
index cc035771..e13cf8c6 100644
--- a/logic/src/main/java/org/itsallcode/whiterabbit/logic/service/plugin/PluginRegistry.java
+++ b/logic/src/main/java/org/itsallcode/whiterabbit/logic/service/plugin/PluginRegistry.java
@@ -48,7 +48,7 @@ private Map<String, AppPluginImpl> loadPlugins()
                 .collect(toMap(AppPluginImpl::getId, Function.identity(), preferExternalJars()));
     }
 
-    private BinaryOperator<AppPluginImpl> preferExternalJars()
+    private static BinaryOperator<AppPluginImpl> preferExternalJars()
     {
         return (a, b) -> {
             LOG.warn("Found two plugins with same ID '{}':\n- {}\n- {}", a.getId(), a, b);
diff --git a/logic/src/main/java/org/itsallcode/whiterabbit/logic/storage/data/JsonFileStorage.java b/logic/src/main/java/org/itsallcode/whiterabbit/logic/storage/data/JsonFileStorage.java
index 707c87da..d9c3f227 100644
--- a/logic/src/main/java/org/itsallcode/whiterabbit/logic/storage/data/JsonFileStorage.java
+++ b/logic/src/main/java/org/itsallcode/whiterabbit/logic/storage/data/JsonFileStorage.java
@@ -96,7 +96,7 @@ public void store(final YearMonth yearMonth, final MonthData monthRecord)
         }
     }
 
-    private void createDirectory(final Path dir)
+    private static void createDirectory(final Path dir)
     {
         if (dir.toFile().isDirectory())
         {
diff --git a/logic/src/test/java/org/itsallcode/whiterabbit/logic/autocomplete/AutocompleteServiceTest.java b/logic/src/test/java/org/itsallcode/whiterabbit/logic/autocomplete/AutocompleteServiceTest.java
index e127eda4..b3bc99e9 100644
--- a/logic/src/test/java/org/itsallcode/whiterabbit/logic/autocomplete/AutocompleteServiceTest.java
+++ b/logic/src/test/java/org/itsallcode/whiterabbit/logic/autocomplete/AutocompleteServiceTest.java
@@ -14,6 +14,7 @@
 import java.time.Period;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Locale;
 import java.util.Optional;
 
 import org.itsallcode.whiterabbit.logic.model.Activity;
@@ -43,7 +44,7 @@ class AutocompleteServiceTest
     @BeforeEach
     void setUp()
     {
-        autocompleteService = new AutocompleteService(storageMock, clockServiceMock);
+        autocompleteService = new AutocompleteService(storageMock, clockServiceMock, Locale.ENGLISH);
     }
 
     @Test
diff --git a/logic/src/test/java/org/itsallcode/whiterabbit/logic/autocomplete/TextIndexTest.java b/logic/src/test/java/org/itsallcode/whiterabbit/logic/autocomplete/TextIndexTest.java
index b2b1364e..e9a175df 100644
--- a/logic/src/test/java/org/itsallcode/whiterabbit/logic/autocomplete/TextIndexTest.java
+++ b/logic/src/test/java/org/itsallcode/whiterabbit/logic/autocomplete/TextIndexTest.java
@@ -3,6 +3,7 @@
 import static org.assertj.core.api.Assertions.assertThat;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.stream.Stream;
 
 import org.junit.jupiter.api.extension.ExtensionContext;
@@ -13,12 +14,12 @@
 
 class TextIndexTest
 {
-
     @ParameterizedTest(name = "[{index}] available values {0}, search text ''{1}''")
     @ArgumentsSource(AutocompleterArgumentsProvider.class)
-    void autocompleter(List<String> availableEntries, String searchText, List<String> expectedResult)
+    void autocompleter(final List<String> availableEntries, final String searchText, final List<String> expectedResult)
     {
-        final List<AutocompleteProposal> entries = TextIndex.build(availableEntries).getEntries(searchText);
+        final List<AutocompleteProposal> entries = TextIndex.build(availableEntries, Locale.ENGLISH)
+                .getEntries(searchText);
         assertThat(entries)
                 .as("autocomplete for available values " + availableEntries + " and search text '" + searchText + "'")
                 .extracting(AutocompleteProposal::getText)
@@ -28,7 +29,7 @@ void autocompleter(List<String> availableEntries, String searchText, List<String
     private static class AutocompleterArgumentsProvider implements ArgumentsProvider
     {
         @Override
-        public Stream<Arguments> provideArguments(ExtensionContext context)
+        public Stream<Arguments> provideArguments(final ExtensionContext context)
         {
             return Stream.of(
                     Arguments.of(List.of(), "text", List.of()),