--- a/mobile/android/base/java/org/mozilla/gecko/db/BrowserDatabaseHelper.java
+++ b/mobile/android/base/java/org/mozilla/gecko/db/BrowserDatabaseHelper.java
@@ -1023,16 +1023,19 @@ public final class BrowserDatabaseHelper
             // We're betting that an error here means that the table already has the column,
             // so we're failing due to the duplicate column name.
             Log.e(LOGTAG, "Error upgrading database from 21 to 22", e);
         }
     }
 
     private void upgradeDatabaseFrom22to23(SQLiteDatabase db) {
         if (didCreateCurrentReadingListTable) {
+            // If we just created this table it is already in the expected >= 23 schema. Trying
+            // to run this migration will crash because columns that were in the <= 22 schema
+            // no longer exist.
             debug("No need to rev reading list schema; we just created with the current schema.");
             return;
         }
 
         debug("Rewriting reading list table.");
         createReadingListTable(db, "tmp_rl");
 
         // Remove indexes. We don't need them now, and we'll be throwing away the table.
@@ -1097,16 +1100,19 @@ public final class BrowserDatabaseHelper
             } catch (Exception e) {
                 Log.e(LOGTAG, "Exception occurred while trying to delete " + file.getPath() + "; ignoring.", e);
             }
         }
     }
 
     private void upgradeDatabaseFrom24to25(SQLiteDatabase db) {
         if (didCreateTabsTable) {
+            // This migration adds a foreign key constraint (the table scheme stays identical, except
+            // for the new constraint) - hence it is safe to run this migration on a newly created tabs
+            // table - but it's unnecessary hence we should avoid doing so.
             debug("No need to rev tabs schema; foreign key constraint exists.");
             return;
         }
 
         debug("Rewriting tabs table.");
         createTabsTable(db, "tmp_tabs");
 
         // Remove indexes. We don't need them now, and we'll be throwing away the table.