diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/generation/type/KeyLength.java b/pgpainless-core/src/main/java/org/pgpainless/key/generation/type/KeyLength.java
deleted file mode 100644
index 1cadfef8..00000000
--- a/pgpainless-core/src/main/java/org/pgpainless/key/generation/type/KeyLength.java
+++ /dev/null
@@ -1,10 +0,0 @@
-// SPDX-FileCopyrightText: 2018 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.key.generation.type;
-
-public interface KeyLength {
-
-    int getLength();
-}
diff --git a/pgpainless-core/src/main/kotlin/org/pgpainless/key/generation/type/KeyLength.kt b/pgpainless-core/src/main/kotlin/org/pgpainless/key/generation/type/KeyLength.kt
new file mode 100644
index 00000000..3f806987
--- /dev/null
+++ b/pgpainless-core/src/main/kotlin/org/pgpainless/key/generation/type/KeyLength.kt
@@ -0,0 +1,10 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.key.generation.type
+
+interface KeyLength {
+    
+    fun getLength(): Int
+}
\ No newline at end of file