# UNDF: UNDF-2026-000000969
--- a/renpy/display/image.py
+++ b/renpy/display/image.py
@@ -980,10 +980,10 @@
                 defaults = f(name)

         # The list of attributes a matching image may have.
-        optional = list(defaults) if defaults else []
+        optional = set(defaults) if defaults else set()

         # The list of attributes a matching image must have.
-        required = []
+        required = set()

         for i in name[1:]:
             if i[0] == "-":
@@ -991,16 +991,16 @@

                 if i in optional:
-                    optional.remove(i)
+                    optional.discard(i)

                 if i in required:
-                    required.remove(i)
+                    required.discard(i)

             else:
-                required.append(i)
+                required.add(i)

         return self.choose_image(nametag, required, optional, name)

     def choose_image(self, tag, required, optional, exception_name):
         # The longest length of an image that matches.
         max_len = -1