diff --git a/aat-lib/src/main/java/ch/bailu/aat_lib/service/tracker/TrackerServiceInterface.java b/aat-lib/src/main/java/ch/bailu/aat_lib/service/tracker/TrackerServiceInterface.java
deleted file mode 100644
index b6d32151b..000000000
--- a/aat-lib/src/main/java/ch/bailu/aat_lib/service/tracker/TrackerServiceInterface.java
+++ /dev/null
@@ -1,7 +0,0 @@
-package ch.bailu.aat_lib.service.tracker;
-
-import ch.bailu.aat_lib.gpx.GpxInformationProvider;
-
-public interface TrackerServiceInterface extends StateInterface, GpxInformationProvider {
-    int getPresetIndex();
-}
diff --git a/aat-lib/src/main/java/ch/bailu/aat_lib/service/tracker/TrackerServiceInterface.kt b/aat-lib/src/main/java/ch/bailu/aat_lib/service/tracker/TrackerServiceInterface.kt
new file mode 100644
index 000000000..f620fc2bd
--- /dev/null
+++ b/aat-lib/src/main/java/ch/bailu/aat_lib/service/tracker/TrackerServiceInterface.kt
@@ -0,0 +1,7 @@
+package ch.bailu.aat_lib.service.tracker
+
+import ch.bailu.aat_lib.gpx.GpxInformationProvider
+
+interface TrackerServiceInterface : StateInterface, GpxInformationProvider {
+    fun getPresetIndex(): Int
+}
diff --git a/aat-lib/src/main/java/ch/bailu/aat_lib/util/WithStatusText.java b/aat-lib/src/main/java/ch/bailu/aat_lib/util/WithStatusText.java
deleted file mode 100644
index 6a7379bc8..000000000
--- a/aat-lib/src/main/java/ch/bailu/aat_lib/util/WithStatusText.java
+++ /dev/null
@@ -1,5 +0,0 @@
-package ch.bailu.aat_lib.util;
-
-public interface WithStatusText {
-    void appendStatusText(StringBuilder builder);
-}
diff --git a/aat-lib/src/main/java/ch/bailu/aat_lib/util/WithStatusText.kt b/aat-lib/src/main/java/ch/bailu/aat_lib/util/WithStatusText.kt
new file mode 100644
index 000000000..0fc0a4c1e
--- /dev/null
+++ b/aat-lib/src/main/java/ch/bailu/aat_lib/util/WithStatusText.kt
@@ -0,0 +1,5 @@
+package ch.bailu.aat_lib.util
+
+interface WithStatusText {
+    fun appendStatusText(builder: StringBuilder)
+}