diff --git a/Lib/mailbox.py b/Lib/mailbox.py
index e23ea8c..8c15301 100644
--- a/Lib/mailbox.py
+++ b/Lib/mailbox.py
@@ -273,6 +273,7 @@ class Maildir(Mailbox):
             else:
                 raise NoSuchMailboxError(self._path)
         self._toc = {}
+        self._toc_read = False
         self._toc_mtimes = {}
         for subdir in ('cur', 'new'):
             self._toc_mtimes[subdir] = os.path.getmtime(self._paths[subdir])
@@ -527,7 +528,7 @@ class Maildir(Mailbox):
                 if mtime > self._toc_mtimes[subdir]:
                     refresh = True
                 self._toc_mtimes[subdir] = mtime
-            if not refresh:
+            if self._toc_read and not refresh:
                 return
         # Refresh toc
         self._toc = {}
@@ -540,6 +541,7 @@ class Maildir(Mailbox):
                 uniq = entry.split(self.colon)[0]
                 self._toc[uniq] = os.path.join(subdir, entry)
         self._last_read = time.time()
+        self._toc_read = True
 
     def _lookup(self, key):
         """Use TOC to return subpath for given key, or raise a KeyError."""
diff --git a/Lib/test/test_mailbox.py b/Lib/test/test_mailbox.py
index fb4812d..e0d8da2 100644
--- a/Lib/test/test_mailbox.py
+++ b/Lib/test/test_mailbox.py
@@ -801,6 +801,25 @@ class TestMaildir(TestMailbox):
                                           key1: os.path.join('new', key1),
                                           key2: os.path.join('new', key2)})
 
+    def test_refresh_after_safety_period(self):
+        # Issue #13254: Call _refresh after the "file system safety
+        # period" of 2 seconds has passed; _toc should still be
+        # updated because this is the first call to _refresh.
+        key0 = self._box.add(self._template % 0)
+        key1 = self._box.add(self._template % 1)
+
+        self._box = self._factory(self._path)
+        self.assertEqual(self._box._toc, {})
+
+        # Emulate sleeping. Instead of sleeping for 2 seconds, use the
+        # skew factor to make _refresh think that the filesystem
+        # safety period has passed and re-reading the _toc is only
+        # required if mtimes differ.
+        self._box._skewfactor = -2
+
+        self._box._refresh()
+        self.assertEqual(sorted(self._box._toc.keys()), sorted([key0, key1]))
+
     def test_lookup(self):
         # Look up message subpaths in the TOC
         self.assertRaises(KeyError, lambda: self._box._lookup('foo'))
@@ -876,6 +895,8 @@ class TestMaildir(TestMailbox):
         self.assertFalse((perms & 0o111)) # Execute bits should all be off.
 
     def test_reread(self):
+        # Do an initial unconditional refresh
+        self._box._refresh()
 
         # Put the last modified times more than two seconds into the past
         # (because mtime may have a two second granularity)