diff --git a/oml/item/scan.py b/oml/item/scan.py
index 4490517..821cec4 100644
--- a/oml/item/scan.py
+++ b/oml/item/scan.py
@@ -32,7 +32,6 @@ def remove_missing(books=None):
     prefix = get_prefix()
     if books is None:
         books = collect_books(prefix)
-    books = [unicodedata.normalize('NFD', path) for path in books]
     with db.session():
         if os.path.exists(prefix):
             logger.debug('scan for removed files')
@@ -42,7 +41,6 @@ def remove_missing(books=None):
                 if state.shutdown:
                     return
                 path = f.fullpath()
-                path = unicodedata.normalize('NFD', path)
                 db_paths.append(path)
                 if f.item:
                     items[path] = f.sha1
@@ -52,7 +50,11 @@ def remove_missing(books=None):
             if dirty:
                 state.db.session.commit()
                 dirty = False
-            removed = set(db_paths) - set(books)
+            nfd_books = {unicodedata.normalize('NFD', path) for path in nfd_books}
+            removed = [
+                path for path in db_paths
+                if unicodedata.normalize('NFD', path) not in nfd_books
+            ]
             if removed:
                 logger.debug('%s files removed', len(removed))
                 ids = [items[path] for path in removed]
@@ -130,6 +132,9 @@ def collect_books(prefix, status=None):
     logger.debug('found %s books', len(books))
     return books
 
+def nfd_same(f1, f2):
+    return unicodedata.normalize('NFD', f1) == unicodedata.normalize('NFD', f2)
+
 def run_scan():
     logger.debug('run_scan')
     prefix = get_prefix()
@@ -150,9 +155,7 @@ def run_scan():
                 if file:
                     f1 = file.fullpath()
                     f2 = os.path.join(prefix, f)
-                    f1 = unicodedata.normalize('NFD', f1)
-                    f2 = unicodedata.normalize('NFD', f2)
-                    if f1 != f2 and os.path.exists(f1) and os.path.exists(f2):
+                    if not nfd_same(f1, f2) and os.path.exists(f1) and os.path.exists(f2):
                         logger.debug('file exists in multiple locations %s', id)
                         logger.debug('"%s" vs "%s"', f1, f2)
                         os.chmod(f2, stat.S_IWRITE)
@@ -163,9 +166,7 @@ def run_scan():
                     if file:
                         f1 = file.fullpath()
                         f2 = os.path.join(prefix, f)
-                        f1 = unicodedata.normalize('NFD', f1)
-                        f2 = unicodedata.normalize('NFD', f2)
-                        if f1 != f2 and os.path.exists(f1) and os.path.exists(f2):
+                        if not nfd_same(f1, f2) and os.path.exists(f1) and os.path.exists(f2):
                             logger.debug('"%s" vs "%s"', f1, f2)
                             os.chmod(f2, stat.S_IWRITE)
                             os.unlink(f2)