diff --git a/main.py b/main.py
index 5ca42aa..40a6b06 100644
--- a/main.py
+++ b/main.py
@@ -194,7 +194,21 @@ async def fetch_post(ctx, md5) -> Optional[dict]:
     if not rows:
         return None
     assert len(rows) == 1
-    return json.loads(rows[0][0])
+    post = json.loads(rows[0][0])
+    post_rating = post["rating"]
+    match post_rating:
+        case "g":
+            rating_tag = "general"
+        case "s":
+            rating_tag = "sensitive"
+        case "q":
+            rating_tag = "questionable"
+        case "e":
+            rating_tag = "explicit"
+        case _:
+            raise AssertionError("invalid post rating {post_rating!r}")
+    post["tag_string"] = post["tag_string"] + " " + rating_tag
+    return post
 
 
 async def insert_post(ctx, post):
@@ -250,8 +264,8 @@ async def fight(ctx):
 
 
 def score(danbooru_tags: Set[str], interrogator_tags: Set[str]) -> decimal.Decimal:
-    tags_in_danbooru = danbooru_tags | interrogator_tags
-    tags_not_in_danbooru = danbooru_tags - interrogator_tags
+    tags_in_danbooru = danbooru_tags.intersection(interrogator_tags)
+    tags_not_in_danbooru = interrogator_tags - danbooru_tags
     return decimal.Decimal(
         len(tags_in_danbooru) - len(tags_not_in_danbooru)
     ) / decimal.Decimal(len(danbooru_tags))