diff --git a/anki/decks.py b/anki/decks.py
index fe1c980bb..efd109853 100644
--- a/anki/decks.py
+++ b/anki/decks.py
@@ -432,13 +432,45 @@ class DeckManager:
         return self.col.db.list("select id from cards where did in "+
                                 ids2str(dids))
 
-    def recoverOrphans(self):
+    def _recoverOrphans(self):
         dids = list(self.decks.keys())
         mod = self.col.db.mod
         self.col.db.execute("update cards set did = 1 where did not in "+
                             ids2str(dids))
         self.col.db.mod = mod
 
+    def _checkDeckTree(self):
+        decks = self.col.decks.all()
+        decks.sort(key=operator.itemgetter('name'))
+        names = set()
+
+        for deck in decks:
+            # two decks with the same name?
+            if deck['name'] in names:
+                print("fix duplicate deck name", deck['name'])
+                deck['name'] += "%d" % intTime(1000)
+                self.save(deck)
+
+            # ensure no sections are blank
+            if not all(deck['name'].split("::")):
+                print("fix deck with missing sections", deck['name'])
+                deck['name'] = "recovered%d" % intTime(1000)
+                self.save(deck)
+
+            # immediate parent must exist
+            if "::" in deck['name']:
+                immediateParent = "::".join(deck['name'].split("::")[:-1])
+                if immediateParent not in names:
+                    print("fix deck with missing parent", deck['name'])
+                    self._ensureParents(deck['name'])
+                    names.add(immediateParent)
+
+            names.add(deck['name'])
+
+    def checkIntegrity(self):
+        self._recoverOrphans()
+        self._checkDeckTree()
+
     # Deck selection
     #############################################################
 
diff --git a/anki/sched.py b/anki/sched.py
index 8dccfea20..bdc83bc9c 100644
--- a/anki/sched.py
+++ b/anki/sched.py
@@ -216,7 +216,7 @@ order by due""" % self._deckLimit(),
     def deckDueList(self):
         "Returns [deckname, did, rev, lrn, new]"
         self._checkDay()
-        self.col.decks.recoverOrphans()
+        self.col.decks.checkIntegrity()
         decks = self.col.decks.all()
         decks.sort(key=itemgetter('name'))
         lims = {}
@@ -228,27 +228,10 @@ order by due""" % self._deckLimit(),
             parts = parts[:-1]
             return "::".join(parts)
         for deck in decks:
-            # if we've already seen the exact same deck name, rename the
-            # invalid duplicate and reload
-            if deck['name'] in lims:
-                deck['name'] += "1"
-                self.col.decks.save(deck)
-                return self.deckDueList()
-            # ensure no sections are blank
-            if not all(deck['name'].split("::")):
-                deck['name'] = "recovered"
-                self.col.decks.save(deck)
-                return self.deckDueList()
-
             p = parent(deck['name'])
             # new
             nlim = self._deckNewLimitSingle(deck)
             if p:
-                if p not in lims:
-                    # if parent was missing, this deck is invalid
-                    deck['name'] = "recovered"
-                    self.col.decks.save(deck)
-                    return self.deckDueList()
                 nlim = min(nlim, lims[p][0])
             new = self._newForDeck(deck['id'], nlim)
             # learning
diff --git a/anki/schedv2.py b/anki/schedv2.py
index e647beb18..74bba3183 100644
--- a/anki/schedv2.py
+++ b/anki/schedv2.py
@@ -205,7 +205,7 @@ order by due""" % self._deckLimit(),
     def deckDueList(self):
         "Returns [deckname, did, rev, lrn, new]"
         self._checkDay()
-        self.col.decks.recoverOrphans()
+        self.col.decks.checkIntegrity()
         decks = self.col.decks.all()
         decks.sort(key=itemgetter('name'))
         lims = {}
@@ -218,27 +218,10 @@ order by due""" % self._deckLimit(),
             return "::".join(parts)
         childMap = self.col.decks.childMap()
         for deck in decks:
-            # if we've already seen the exact same deck name, rename the
-            # invalid duplicate and reload
-            if deck['name'] in lims:
-                deck['name'] += "1"
-                self.col.decks.save(deck)
-                return self.deckDueList()
-            # ensure no sections are blank
-            if not all(deck['name'].split("::")):
-                deck['name'] = "recovered"
-                self.col.decks.save(deck)
-                return self.deckDueList()
-
             p = parent(deck['name'])
             # new
             nlim = self._deckNewLimitSingle(deck)
             if p:
-                if p not in lims:
-                    # if parent was missing, this deck is invalid
-                    deck['name'] = "recovered"
-                    self.col.decks.save(deck)
-                    return self.deckDueList()
                 nlim = min(nlim, lims[p][0])
             new = self._newForDeck(deck['id'], nlim)
             # learning