diff --git a/app/src/androidTest/java/im/conversations/android/xmpp/MessageTransformationTest.java b/app/src/androidTest/java/im/conversations/android/xmpp/MessageTransformationTest.java
index 11a435e41..0c0771f5c 100644
--- a/app/src/androidTest/java/im/conversations/android/xmpp/MessageTransformationTest.java
+++ b/app/src/androidTest/java/im/conversations/android/xmpp/MessageTransformationTest.java
@@ -71,7 +71,12 @@ public class MessageTransformationTest {
         reaction.setContent("Y");
         this.transformer.transform(
                 MessageTransformation.of(
-                        reactionMessage, Instant.now(), REMOTE, "stanza-b", null, null));
+                        reactionMessage,
+                        Instant.now(),
+                        REMOTE,
+                        "stanza-b",
+                        reactionMessage.getFrom().asBareJid(),
+                        null));
         final var originalMessage = new Message();
         originalMessage.setId("1");
         originalMessage.setTo(REMOTE);
@@ -80,7 +85,12 @@ public class MessageTransformationTest {
         body.setContent(GREETING);
         this.transformer.transform(
                 MessageTransformation.of(
-                        originalMessage, Instant.now(), REMOTE, "stanza-a", null, null));
+                        originalMessage,
+                        Instant.now(),
+                        REMOTE,
+                        "stanza-a",
+                        originalMessage.getFrom().asBareJid(),
+                        null));
 
         final var messages = database.messageDao().getMessages(1L);
         Assert.assertEquals(1, messages.size());
@@ -151,7 +161,12 @@ public class MessageTransformationTest {
 
         this.transformer.transform(
                 MessageTransformation.of(
-                        messageCorrection, Instant.now(), REMOTE, "stanza-a", null, null));
+                        messageCorrection,
+                        Instant.now(),
+                        REMOTE,
+                        "stanza-a",
+                        messageCorrection.getFrom().asBareJid(),
+                        null));
 
         // the correction should not show up as a message
         Assert.assertEquals(0, database.messageDao().getMessages(1L).size());
@@ -164,7 +179,12 @@ public class MessageTransformationTest {
 
         this.transformer.transform(
                 MessageTransformation.of(
-                        messageWithTypo, Instant.now(), REMOTE, "stanza-b", null, null));
+                        messageWithTypo,
+                        Instant.now(),
+                        REMOTE,
+                        "stanza-b",
+                        messageWithTypo.getFrom().asBareJid(),
+                        null));
 
         final var messages = database.messageDao().getMessages(1L);
 
@@ -187,7 +207,12 @@ public class MessageTransformationTest {
 
         this.transformer.transform(
                 MessageTransformation.of(
-                        messageWithTypo, Instant.now(), REMOTE, "stanza-a", null, null));
+                        messageWithTypo,
+                        Instant.now(),
+                        REMOTE,
+                        "stanza-a",
+                        messageWithTypo.getFrom().asBareJid(),
+                        null));
 
         Assert.assertEquals(1, database.messageDao().getMessages(1L).size());
 
@@ -200,7 +225,12 @@ public class MessageTransformationTest {
 
         this.transformer.transform(
                 MessageTransformation.of(
-                        messageCorrection, Instant.now(), REMOTE, "stanza-b", null, null));
+                        messageCorrection,
+                        Instant.now(),
+                        REMOTE,
+                        "stanza-b",
+                        messageCorrection.getFrom().asBareJid(),
+                        null));
 
         final var messages = database.messageDao().getMessages(1L);
 
@@ -504,7 +534,8 @@ public class MessageTransformationTest {
         m1.addExtension(new Body("It is raining outside"));
 
         this.transformer.transform(
-                MessageTransformation.of(m1, Instant.now(), REMOTE, null, null, null));
+                MessageTransformation.of(
+                        m1, Instant.now(), REMOTE, null, m1.getFrom().asBareJid(), null));
 
         final var m2 = new Message();
         m2.setTo(ACCOUNT);
@@ -512,7 +543,8 @@ public class MessageTransformationTest {
         m2.addExtension(new Retract()).setId("m1");
 
         this.transformer.transform(
-                MessageTransformation.of(m2, Instant.now(), REMOTE, null, null, null));
+                MessageTransformation.of(
+                        m2, Instant.now(), REMOTE, null, m2.getFrom().asBareJid(), null));
 
         final var messages = database.messageDao().getMessages(1L);
         final var message = Iterables.getOnlyElement(messages);
diff --git a/app/src/main/java/im/conversations/android/transformer/MessageTransformation.java b/app/src/main/java/im/conversations/android/transformer/MessageTransformation.java
index 35b4bf542..36cabc084 100644
--- a/app/src/main/java/im/conversations/android/transformer/MessageTransformation.java
+++ b/app/src/main/java/im/conversations/android/transformer/MessageTransformation.java
@@ -1,6 +1,7 @@
 package im.conversations.android.transformer;
 
 import androidx.annotation.NonNull;
+import com.google.common.base.Preconditions;
 import com.google.common.collect.Collections2;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
@@ -114,6 +115,10 @@ public class MessageTransformation extends Transformation {
         final var messageId = message.getId();
         final ImmutableList.Builder<Extension> extensionListBuilder = new ImmutableList.Builder<>();
         final Collection<DeliveryReceiptRequest> requests;
+        if (type != Message.Type.GROUPCHAT) {
+            Preconditions.checkNotNull(
+                    senderId, "senderId must not be null for anything but group chat messages");
+        }
         if (type == Message.Type.ERROR) {
             extensionListBuilder.add(message.getError());
             requests = Collections.emptyList();