diff --git a/sop-java/src/main/java/sop/DecryptionResult.java b/sop-java/src/main/java/sop/DecryptionResult.java
deleted file mode 100644
index 4f0e1ab..0000000
--- a/sop-java/src/main/java/sop/DecryptionResult.java
+++ /dev/null
@@ -1,29 +0,0 @@
-// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package sop;
-
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import sop.util.Optional;
-
-public class DecryptionResult {
-
-    private final Optional<SessionKey> sessionKey;
-    private final List<Verification> verifications;
-
-    public DecryptionResult(SessionKey sessionKey, List<Verification> verifications) {
-        this.sessionKey = Optional.ofNullable(sessionKey);
-        this.verifications = Collections.unmodifiableList(verifications);
-    }
-
-    public Optional<SessionKey> getSessionKey() {
-        return sessionKey;
-    }
-
-    public List<Verification> getVerifications() {
-        return new ArrayList<>(verifications);
-    }
-}
diff --git a/sop-java/src/main/kotlin/sop/DecryptionResult.kt b/sop-java/src/main/kotlin/sop/DecryptionResult.kt
new file mode 100644
index 0000000..1ba98bb
--- /dev/null
+++ b/sop-java/src/main/kotlin/sop/DecryptionResult.kt
@@ -0,0 +1,16 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package sop
+
+import sop.util.Optional
+
+data class DecryptionResult
+internal constructor(val sessionKey: Optional<SessionKey>, val verifications: List<Verification>) {
+
+    constructor(
+        sessionKey: SessionKey?,
+        verifications: List<Verification>
+    ) : this(Optional.ofNullable(sessionKey), verifications)
+}