diff --git a/dlibrary/dlibrary.py b/dlibrary/dlibrary.py
index 4e2eea6..8dee4bd 100755
--- a/dlibrary/dlibrary.py
+++ b/dlibrary/dlibrary.py
@@ -26,7 +26,7 @@ FAKKU_ID_REGEX = re.compile('.*_FAKKU$')
 
 TEXTLESS_REGEX = re.compile('(台詞|セリフ)(な|無)し|notext|textless')
 EPILOGUE_REGEX = re.compile('after|後日談')
-ALT_VERSIONS = ['褐色', '日焼け', 'pink', '金髪', '白肌']
+ALT_VERSIONS = ['褐色', '日焼け', 'pink', '金髪', '白肌', 'うつろ目']
 
 IMAGE_FILE_EXTENSIONS = ['.png', '.jpg', '.jpeg', '.gif', '.tiff']
 
@@ -202,8 +202,11 @@ def complete_prefix_number_ordering(entries):
 
     entries_by_version = {}
     for entry in entries:
-        version = next(ver for ver in (ALT_VERSIONS + ['']) if ver in entry.name)
-        entries_by_version.setdefault(version, []).append(entry)
+        version_code = 0
+        for (i, version) in enumerate(ALT_VERSIONS):
+            if version in entry.name:
+                version_code |= (1 << i)
+        entries_by_version.setdefault(version_code, []).append(entry)
 
     numberings_by_version = {ver: unique_hierarchical_prefix_numbering(entries_by_version[ver]) for ver in entries_by_version}
 
@@ -212,6 +215,7 @@ def complete_prefix_number_ordering(entries):
         if numbering is None:
             return None
         unified_indices |= set(numbering.keys())
+    unified_indices.discard(None)
     unified_indices = list(unified_indices)
     unified_indices.sort()
 
@@ -225,6 +229,8 @@ def complete_prefix_number_ordering(entries):
                         return None
                     break
 
+    unified_indices.append(None)
+
     versions = list(numberings_by_version.keys())
     versions.sort()
 
@@ -245,6 +251,9 @@ def complete_prefix_number_ordering(entries):
     return result
 
 def unique_hierarchical_prefix_numbering(entries, start_point=0):
+    if len(entries) == 1 and not NUMBER_REGEX.search(entries[0].name):
+        return {None: entries}
+
     longest_entry = max(entries, key=lambda e: len(e.name))
     matches = reversed(list(NUMBER_REGEX.finditer(longest_entry.name)))
     for m in matches: