diff --git a/app/src/androidTest/scala/com.nutomic.ensichat.messages/MessageStoreTest.scala b/app/src/androidTest/scala/com.nutomic.ensichat.messages/MessageStoreTest.scala
index 113fdf5..43545f8 100644
--- a/app/src/androidTest/scala/com.nutomic.ensichat.messages/MessageStoreTest.scala
+++ b/app/src/androidTest/scala/com.nutomic.ensichat.messages/MessageStoreTest.scala
@@ -7,6 +7,7 @@ import android.database.DatabaseErrorHandler
 import android.database.sqlite.SQLiteDatabase
 import android.test.AndroidTestCase
 import android.test.mock.MockContext
+import android.util.Log
 import com.nutomic.ensichat.bluetooth.Device
 import com.nutomic.ensichat.messages.MessageTest._
 import junit.framework.Assert._
@@ -38,20 +39,20 @@ class MessageStoreTest extends AndroidTestCase {
   }
 
   def testCount(): Unit = {
-    val msg1 = MessageStore.getMessages(new Device.ID("one"), 1)
+    val msg1 = MessageStore.getMessages(m1.sender, 1)
     assertEquals(1, msg1.size)
 
-    val msg2 = MessageStore.getMessages(new Device.ID("one"), 3)
+    val msg2 = MessageStore.getMessages(m1.sender, 3)
     assertEquals(2, msg2.size)
   }
 
   def testOrder(): Unit = {
-    val msg = MessageStore.getMessages(new Device.ID("two"), 1)
+    val msg = MessageStore.getMessages(m1.receiver, 1)
     assertTrue(msg.contains(m3))
   }
 
   def testSelect(): Unit = {
-    val msg = MessageStore.getMessages(new Device.ID("two"), 2)
+    val msg = MessageStore.getMessages(m1.receiver, 2)
     assertTrue(msg.contains(m1))
     assertTrue(msg.contains(m3))
   }
diff --git a/app/src/androidTest/scala/com.nutomic.ensichat.messages/MessageTest.scala b/app/src/androidTest/scala/com.nutomic.ensichat.messages/MessageTest.scala
index d9a5336..2802570 100644
--- a/app/src/androidTest/scala/com.nutomic.ensichat.messages/MessageTest.scala
+++ b/app/src/androidTest/scala/com.nutomic.ensichat.messages/MessageTest.scala
@@ -12,13 +12,13 @@ import scala.collection.immutable.TreeSet
 
 object MessageTest {
 
-  val m1 = new TextMessage(new Device.ID("one"), new Device.ID("two"),
+  val m1 = new TextMessage(new Device.ID("AA:AA:AA:AA:AA:AA"), new Device.ID("BB:BB:BB:BB:BB:BB"),
     new GregorianCalendar(2014, 10, 29).getTime, "first")
 
-  val m2 = new TextMessage(new Device.ID("one"), new Device.ID("three"),
+  val m2 = new TextMessage(new Device.ID("AA:AA:AA:AA:AA:AA"), new Device.ID("CC:CC:CC:CC:CC:CC"),
     new GregorianCalendar(2014, 10, 30).getTime, "second")
 
-  val m3 = new TextMessage(new Device.ID("four"), new Device.ID("two"),
+  val m3 = new TextMessage(new Device.ID("DD:DD:DD:DD:DD:DD"), new Device.ID("BB:BB:BB:BB:BB:BB"),
     new GregorianCalendar(2014, 10, 31).getTime, "third")
 
 
diff --git a/app/src/main/scala/com/nutomic/ensichat/bluetooth/Device.scala b/app/src/main/scala/com/nutomic/ensichat/bluetooth/Device.scala
index 9761047..afc0f60 100644
--- a/app/src/main/scala/com/nutomic/ensichat/bluetooth/Device.scala
+++ b/app/src/main/scala/com/nutomic/ensichat/bluetooth/Device.scala
@@ -10,12 +10,17 @@ object Device {
    * @param Id A bluetooth device address.
    */
   class ID(private val Id: String) {
+    require(Id.matches("([A-Z0-9][A-Z0-9]:){5}[A-Z0-9][A-Z0-9]"), "Invalid device ID format")
+
     override def hashCode = Id.hashCode
+
     override def equals(a: Any) = a match {
       case other: Device.ID => Id == other.Id
       case _ => false
     }
+
     override def toString = Id
+
   }
 
 }