diff --git a/app/src/main/java/com/etesync/syncadapter/Constants.java b/app/src/main/java/com/etesync/syncadapter/Constants.java
index 32de59f2..8b203b3b 100644
--- a/app/src/main/java/com/etesync/syncadapter/Constants.java
+++ b/app/src/main/java/com/etesync/syncadapter/Constants.java
@@ -38,6 +38,8 @@ public class Constants {
 
     public static final Uri serviceUrl = Uri.parse((DEBUG_REMOTE_URL == null) ? "https://api.etesync.com/" : DEBUG_REMOTE_URL);
 
+    public static final String PRODID_BASE = "-//EteSync//" + BuildConfig.APPLICATION_ID + " " + BuildConfig.VERSION_NAME;
+
     public static final int DEFAULT_SYNC_INTERVAL = 4 * 3600;  // 4 hours
     public static final long DEFAULT_RETRY_DELAY = 30 * 60; // 30 minutes
 
diff --git a/app/src/main/java/com/etesync/syncadapter/resource/LocalContact.java b/app/src/main/java/com/etesync/syncadapter/resource/LocalContact.java
index 6ce19d76..6ab6b65c 100644
--- a/app/src/main/java/com/etesync/syncadapter/resource/LocalContact.java
+++ b/app/src/main/java/com/etesync/syncadapter/resource/LocalContact.java
@@ -22,6 +22,8 @@ import android.support.annotation.Nullable;
 import android.text.TextUtils;
 
 import com.etesync.syncadapter.App;
+import com.etesync.syncadapter.BuildConfig;
+import com.etesync.syncadapter.Constants;
 import com.etesync.syncadapter.model.UnknownProperties;
 
 import java.io.ByteArrayOutputStream;
@@ -39,12 +41,16 @@ import at.bitfire.vcard4android.BatchOperation;
 import at.bitfire.vcard4android.CachedGroupMembership;
 import at.bitfire.vcard4android.Contact;
 import at.bitfire.vcard4android.ContactsStorageException;
+import ezvcard.Ezvcard;
 import ezvcard.VCardVersion;
 import lombok.Cleanup;
 
 import static at.bitfire.vcard4android.GroupMethod.GROUP_VCARDS;
 
 public class LocalContact extends AndroidContact implements LocalResource {
+    static {
+        Contact.productID = Constants.PRODID_BASE + "//vcard4android ez-vcard/0.10.x";
+    }
     public static final String COLUMN_HASHCODE = ContactsContract.RawContacts.SYNC3;
 
     private boolean saveAsDirty = false; // When true, the resource will be saved as dirty
diff --git a/app/src/main/java/com/etesync/syncadapter/resource/LocalEvent.java b/app/src/main/java/com/etesync/syncadapter/resource/LocalEvent.java
index 02d43d2a..05d04c4b 100644
--- a/app/src/main/java/com/etesync/syncadapter/resource/LocalEvent.java
+++ b/app/src/main/java/com/etesync/syncadapter/resource/LocalEvent.java
@@ -21,6 +21,9 @@ import android.support.annotation.NonNull;
 import android.text.TextUtils;
 
 import com.etesync.syncadapter.App;
+import com.etesync.syncadapter.Constants;
+
+import net.fortuna.ical4j.model.property.ProdId;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -38,6 +41,9 @@ import lombok.Setter;
 
 @TargetApi(17)
 public class LocalEvent extends AndroidEvent implements LocalResource {
+    static {
+        Event.prodId = new ProdId(Constants.PRODID_BASE + "//ical4android ical4j/2.x");
+    }
     static final String COLUMN_ETAG = CalendarContract.Events.SYNC_DATA1,
             COLUMN_UID = Build.VERSION.SDK_INT >= 17 ? Events.UID_2445 : Events.SYNC_DATA2,
             COLUMN_SEQUENCE = CalendarContract.Events.SYNC_DATA3;
diff --git a/app/src/main/java/com/etesync/syncadapter/resource/LocalTask.java b/app/src/main/java/com/etesync/syncadapter/resource/LocalTask.java
index d7652ddd..101fa8a2 100644
--- a/app/src/main/java/com/etesync/syncadapter/resource/LocalTask.java
+++ b/app/src/main/java/com/etesync/syncadapter/resource/LocalTask.java
@@ -15,6 +15,9 @@ import android.provider.CalendarContract.Events;
 import android.support.annotation.NonNull;
 
 import com.etesync.syncadapter.App;
+import com.etesync.syncadapter.Constants;
+
+import net.fortuna.ical4j.model.property.ProdId;
 
 import org.dmfs.provider.tasks.TaskContract.Tasks;
 
@@ -32,6 +35,10 @@ import lombok.Getter;
 import lombok.Setter;
 
 public class LocalTask extends AndroidTask implements LocalResource {
+    static {
+        Task.prodId = new ProdId(Constants.PRODID_BASE + "//ical4android ical4j/2.x");
+    }
+
     @Getter
     protected String uuid;