diff --git a/sop-java/src/main/java/sop/enums/SignAs.java b/sop-java/src/main/java/sop/enums/SignAs.java
deleted file mode 100644
index 1174098..0000000
--- a/sop-java/src/main/java/sop/enums/SignAs.java
+++ /dev/null
@@ -1,23 +0,0 @@
-// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package sop.enums;
-
-public enum SignAs {
-    /**
-     * Signature is made over the binary message.
-     */
-    Binary,
-
-    /**
-     * Signature is made over the message in text mode.
-     */
-    Text,
-    ;
-
-    @Override
-    public String toString() {
-        return super.toString().toLowerCase();
-    }
-}
diff --git a/sop-java/src/main/kotlin/sop/enums/SignAs.kt b/sop-java/src/main/kotlin/sop/enums/SignAs.kt
new file mode 100644
index 0000000..832e831
--- /dev/null
+++ b/sop-java/src/main/kotlin/sop/enums/SignAs.kt
@@ -0,0 +1,12 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package sop.enums
+
+enum class SignAs {
+    /** Signature is made over the binary message. */
+    binary,
+    /** Signature is made over the message in text mode. */
+    text
+}
diff --git a/sop-java/src/testFixtures/java/sop/testsuite/operation/DetachedSignDetachedVerifyTest.java b/sop-java/src/testFixtures/java/sop/testsuite/operation/DetachedSignDetachedVerifyTest.java
index e715c14..e404599 100644
--- a/sop-java/src/testFixtures/java/sop/testsuite/operation/DetachedSignDetachedVerifyTest.java
+++ b/sop-java/src/testFixtures/java/sop/testsuite/operation/DetachedSignDetachedVerifyTest.java
@@ -62,7 +62,7 @@ public class DetachedSignDetachedVerifyTest extends AbstractSOPTest {
 
         byte[] signature = sop.detachedSign()
                 .key(TestData.ALICE_KEY.getBytes(StandardCharsets.UTF_8))
-                .mode(SignAs.Text)
+                .mode(SignAs.text)
                 .data(message)
                 .toByteArrayAndResult()
                 .getBytes();