diff --git a/MyTracks/proguard.cfg b/MyTracks/proguard.cfg
index 65fa34cbb..8a6087a72 100644
--- a/MyTracks/proguard.cfg
+++ b/MyTracks/proguard.cfg
@@ -15,11 +15,17 @@
 -dontwarn org.codehaus.**
 -dontwarn com.google.appengine.**
 
+# Make our stack traces useful
+# Line numbers will be correct, file names will be replaced by "MT" since the
+# class name is enough to get the file name.
+-renamesourcefileattribute MT
+-keepattributes SourceFile,LineNumberTable
+
 # Keep everything android references from XMLs
 -keep public class * extends android.app.Activity
 -keep public class * extends android.app.Application
 -keep public class * extends android.app.Service
--keep public class * extends android.app,backup.BackupAgent
+-keep public class * extends android.app.backup.BackupAgent
 -keep public class * extends android.content.BroadcastReceiver
 -keep public class * extends android.content.ContentProvider
 -keep public class * extends android.preference.Preference