diff --git a/ultrasonic/src/main/java/org/moire/ultrasonic/service/Downloader.java b/ultrasonic/src/main/java/org/moire/ultrasonic/service/Downloader.kt
similarity index 100%
rename from ultrasonic/src/main/java/org/moire/ultrasonic/service/Downloader.java
rename to ultrasonic/src/main/java/org/moire/ultrasonic/service/Downloader.kt