diff --git a/src/main/java/de/dennisguse/opentracks/data/models/TrackPoint.java b/src/main/java/de/dennisguse/opentracks/data/models/TrackPoint.java
index 90aa92d0a..393d49176 100644
--- a/src/main/java/de/dennisguse/opentracks/data/models/TrackPoint.java
+++ b/src/main/java/de/dennisguse/opentracks/data/models/TrackPoint.java
@@ -35,7 +35,7 @@ import java.util.Optional;
 public class TrackPoint {
 
     @Nullable
-    private TrackPoint.Id id;
+    private final TrackPoint.Id id;
 
     //Requires: position.time must be non-null
     @NonNull
diff --git a/src/main/java/de/dennisguse/opentracks/io/file/importer/ImportActivity.java b/src/main/java/de/dennisguse/opentracks/io/file/importer/ImportActivity.java
index 9138887f7..a3c33f20c 100644
--- a/src/main/java/de/dennisguse/opentracks/io/file/importer/ImportActivity.java
+++ b/src/main/java/de/dennisguse/opentracks/io/file/importer/ImportActivity.java
@@ -97,9 +97,7 @@ public class ImportActivity extends AbstractActivity {
 
         importer = new Importer(this, documentFiles);
         importer.getLiveData()
-                .observe(this, summary -> {
-                    setProgress(summary);
-                });
+                .observe(this, summary -> setProgress(summary));
         importer.startImport();
 
         //Works for a directory, but we might have received multiple files via SEND_MULTIPLE.
diff --git a/src/main/java/de/dennisguse/opentracks/settings/LocalePreference.java b/src/main/java/de/dennisguse/opentracks/settings/LocalePreference.java
index 95687143c..83c2f5658 100644
--- a/src/main/java/de/dennisguse/opentracks/settings/LocalePreference.java
+++ b/src/main/java/de/dennisguse/opentracks/settings/LocalePreference.java
@@ -29,7 +29,7 @@ import de.dennisguse.opentracks.R;
 
 public class LocalePreference extends ListPreference {
 
-    private String TAG = LocalePreference.class.getSimpleName();
+    private final String TAG = LocalePreference.class.getSimpleName();
 
     public LocalePreference(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
         super(context, attrs, defStyleAttr, defStyleRes);
diff --git a/src/main/java/de/dennisguse/opentracks/util/PermissionRequester.java b/src/main/java/de/dennisguse/opentracks/util/PermissionRequester.java
index d8a9fe02c..f99f10fb4 100644
--- a/src/main/java/de/dennisguse/opentracks/util/PermissionRequester.java
+++ b/src/main/java/de/dennisguse/opentracks/util/PermissionRequester.java
@@ -95,7 +95,7 @@ public class PermissionRequester {
         ArrayList<String> recording = new ArrayList<>(GPS_PERMISSION);
         recording.addAll(BLUETOOTH_PERMISSIONS);
 
-        RECORDING_PERMISSIONS = Collections.unmodifiableList(new ArrayList<>(recording));
+        RECORDING_PERMISSIONS = List.copyOf(recording);
 
         recording.addAll(NOTIFICATION_PERMISSIONS);