diff --git a/app/src/main/java/com/murrayc/galaxyzoo/app/BaseActivity.java b/app/src/main/java/com/murrayc/galaxyzoo/app/BaseActivity.java
index a9204ad8..553fc9e1 100644
--- a/app/src/main/java/com/murrayc/galaxyzoo/app/BaseActivity.java
+++ b/app/src/main/java/com/murrayc/galaxyzoo/app/BaseActivity.java
@@ -94,6 +94,9 @@ public boolean onOptionsItemSelected(MenuItem item) {
         final int id = item.getItemId();
 
         if (id == android.R.id.home) {
+            //We can use this instead of more complex code, checking NavUtils.shouldUpRecreateTask(),
+            //because we know that our activities will never be opened from another app.
+            //See http://developer.android.com/training/implementing-navigation/ancestral.html.
             NavUtils.navigateUpFromSameTask(this);
             return true;
         }