diff --git a/src/main/java/eu/siacs/conversations/xmpp/jingle/JingleConnectionManager.java b/src/main/java/eu/siacs/conversations/xmpp/jingle/JingleConnectionManager.java
index 8ba989270..38c98082d 100644
--- a/src/main/java/eu/siacs/conversations/xmpp/jingle/JingleConnectionManager.java
+++ b/src/main/java/eu/siacs/conversations/xmpp/jingle/JingleConnectionManager.java
@@ -122,8 +122,8 @@ public class JingleConnectionManager extends AbstractConnectionManager {
     }
 
     public void deliverIbbPacket(Account account, IqPacket packet) {
-        String sid = null;
-        Element payload = null;
+        final String sid;
+        final Element payload;
         if (packet.hasChild("open", Namespace.IBB)) {
             payload = packet.findChild("open", Namespace.IBB);
             sid = payload.getAttribute("sid");
@@ -133,6 +133,9 @@ public class JingleConnectionManager extends AbstractConnectionManager {
         } else if (packet.hasChild("close", Namespace.IBB)) {
             payload = packet.findChild("close", Namespace.IBB);
             sid = payload.getAttribute("sid");
+        } else {
+            payload = null;
+            sid = null;
         }
         if (sid != null) {
             for (final AbstractJingleConnection connection : this.connections.values()) {
@@ -140,7 +143,10 @@ public class JingleConnectionManager extends AbstractConnectionManager {
                     final JingleFileTransferConnection fileTransfer = (JingleFileTransferConnection) connection;
                     final JingleTransport transport = fileTransfer.getTransport();
                     if (transport instanceof JingleInBandTransport) {
-                        ((JingleInBandTransport) transport).deliverPayload(packet, payload);
+                        final JingleInBandTransport inBandTransport = (JingleInBandTransport) transport;
+                        if (inBandTransport.matches(account, sid)) {
+                            inBandTransport.deliverPayload(packet, payload);
+                        }
                         return;
                     }
                 }
diff --git a/src/main/java/eu/siacs/conversations/xmpp/jingle/JingleInBandTransport.java b/src/main/java/eu/siacs/conversations/xmpp/jingle/JingleInBandTransport.java
index c5eaca072..fbc1ad95f 100644
--- a/src/main/java/eu/siacs/conversations/xmpp/jingle/JingleInBandTransport.java
+++ b/src/main/java/eu/siacs/conversations/xmpp/jingle/JingleInBandTransport.java
@@ -3,6 +3,8 @@ package eu.siacs.conversations.xmpp.jingle;
 import android.util.Base64;
 import android.util.Log;
 
+import com.google.common.base.Preconditions;
+
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -77,6 +79,10 @@ public class JingleInBandTransport extends JingleTransport {
         this.account.getXmppConnection().sendIqPacket(iq, null);
     }
 
+    public boolean matches(final Account account, final String sessionId) {
+        return this.account == account && this.sessionId.equals(sessionId);
+    }
+
     public void connect(final OnTransportConnected callback) {
         IqPacket iq = new IqPacket(IqPacket.TYPE.SET);
         iq.setTo(this.counterpart);
@@ -96,7 +102,7 @@ public class JingleInBandTransport extends JingleTransport {
 
     @Override
     public void receive(DownloadableFile file, OnFileTransmissionStatusChanged callback) {
-        this.onFileTransmissionStatusChanged = callback;
+        this.onFileTransmissionStatusChanged = Preconditions.checkNotNull(callback);
         this.file = file;
         try {
             this.digest = MessageDigest.getInstance("SHA-1");
@@ -116,7 +122,7 @@ public class JingleInBandTransport extends JingleTransport {
 
     @Override
     public void send(DownloadableFile file, OnFileTransmissionStatusChanged callback) {
-        this.onFileTransmissionStatusChanged = callback;
+        this.onFileTransmissionStatusChanged = Preconditions.checkNotNull(callback);
         this.file = file;
         try {
             this.remainingSize = this.file.getExpectedSize();
@@ -205,7 +211,7 @@ public class JingleInBandTransport extends JingleTransport {
                 connection.updateProgress((int) ((((double) (this.fileSize - this.remainingSize)) / this.fileSize) * 100));
             }
         } catch (Exception e) {
-            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": " + e.getMessage());
+            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": " + e.getMessage(), e);
             FileBackend.close(fileOutputStream);
             this.onFileTransmissionStatusChanged.onFileTransferAborted();
         }