diff --git a/src/calibre/db/cache.py b/src/calibre/db/cache.py
index c4cb1036dd..73a05d493f 100644
--- a/src/calibre/db/cache.py
+++ b/src/calibre/db/cache.py
@@ -52,6 +52,7 @@ from calibre.ebooks.metadata.opf2 import metadata_to_opf
 from calibre.ptempfile import PersistentTemporaryFile, SpooledTemporaryFile, base_dir
 from calibre.utils.config import prefs, tweaks
 from calibre.utils.date import UNDEFINED_DATE, now as nowf, utcnow
+from calibre.utils.filenames import make_long_path_useable
 from calibre.utils.icu import lower as icu_lower, sort_key
 from calibre.utils.localization import canonicalize_lang
 from polyglot.builtins import cmp, iteritems, itervalues, string_or_bytes
@@ -1950,7 +1951,7 @@ class Cache:
             # message in the GUI during the processing.
             npath = run_import_plugins(stream_or_path, fmt)
             fmt = os.path.splitext(npath)[-1].lower().replace('.', '').upper()
-            stream_or_path = open(npath, 'rb')
+            stream_or_path = open(make_long_path_useable(npath), 'rb')
             needs_close = True
             fmt = check_ebook_format(stream_or_path, fmt)
 
@@ -1972,7 +1973,7 @@ class Cache:
             if hasattr(stream_or_path, 'read'):
                 stream = stream_or_path
             else:
-                stream = open(stream_or_path, 'rb')
+                stream = open(make_long_path_useable(stream_or_path), 'rb')
                 needs_close = True
             try:
                 size, fname = self._do_add_format(book_id, fmt, stream, name)
diff --git a/src/calibre/gui2/auto_add.py b/src/calibre/gui2/auto_add.py
index 888045d4a3..e78c9070be 100644
--- a/src/calibre/gui2/auto_add.py
+++ b/src/calibre/gui2/auto_add.py
@@ -242,7 +242,7 @@ class AutoAdder(QObject):
             try:
                 with open(sz, 'rb') as f:
                     sz = int(f.read())
-                if sz != os.stat(paths[0]).st_size:
+                if sz != os.stat(make_long_path_useable(paths[0])).st_size:
                     raise Exception('Looks like the file was written to after'
                             ' we tried to read metadata')
             except:
@@ -282,7 +282,7 @@ class AutoAdder(QObject):
                 duplicates.append(dups)
 
             try:
-                os.remove(path_to_remove)
+                os.remove(make_long_path_useable(path_to_remove))
                 self.worker.staging.remove(fname)
             except:
                 import traceback