diff --git a/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlMessage.java b/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlMessage.java
index bba24d90b5a5c8899e7441135b66e29144b12925..790e33bd65d764c21faa24d730720d53fcfdaf53 100644
--- a/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlMessage.java
+++ b/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlMessage.java
@@ -146,6 +146,8 @@ public class XmppAxolotlMessage {
     }
 
     void encrypt(final String plaintext) throws CryptoFailedException {
+        if (plaintext == null) return;
+
         try {
             SecretKey secretKey = new SecretKeySpec(innerKey, KEYTYPE);
             IvParameterSpec ivSpec = new IvParameterSpec(iv);