diff --git a/src/invidious/routes/api/v1/authenticated.cr b/src/invidious/routes/api/v1/authenticated.cr
index d006d5f2c..ebbbc2a76 100644
--- a/src/invidious/routes/api/v1/authenticated.cr
+++ b/src/invidious/routes/api/v1/authenticated.cr
@@ -98,12 +98,12 @@ module Invidious::Routes::API::V1::Authenticated
       return error_json(409, "Watch history is disabled in preferences.")
     end
 
-    id = env.params.url["id"]
-    if !id.match(/^[a-zA-Z0-9_-]{11}$/)
-      return error_json(400, "Invalid video id.")
+    video_id = env.params.url["id"]
+    unless video_id && validate_video_id(video_id)
+      return error_json(400, InvalidVideoID.new(video_id))
     end
 
-    Invidious::Database::Users.mark_unwatched(user, id)
+    Invidious::Database::Users.mark_unwatched(user, video_id)
     env.response.status_code = 204
   end
 
diff --git a/src/invidious/routes/api/v1/videos.cr b/src/invidious/routes/api/v1/videos.cr
index bd76b005b..5600e30dc 100644
--- a/src/invidious/routes/api/v1/videos.cr
+++ b/src/invidious/routes/api/v1/videos.cr
@@ -257,11 +257,11 @@ module Invidious::Routes::API::V1::Videos
   def self.annotations(env)
     env.response.content_type = "text/xml"
 
-    id = env.params.url["id"]
+    video_id = env.params.url["id"]
     source = env.params.query["source"]?
     source ||= "archive"
 
-    if !id.match(/[a-zA-Z0-9_-]{11}/)
+    unless video_id && validate_video_id(video_id)
       haltf env, 400
     end
 
@@ -269,21 +269,21 @@ module Invidious::Routes::API::V1::Videos
 
     case source
     when "archive"
-      if CONFIG.cache_annotations && (cached_annotation = Invidious::Database::Annotations.select(id))
+      if CONFIG.cache_annotations && (cached_annotation = Invidious::Database::Annotations.select(video_id))
         annotations = cached_annotation.annotations
       else
-        index = CHARS_SAFE.index!(id[0]).to_s.rjust(2, '0')
+        index = CHARS_SAFE.index!(video_id[0]).to_s.rjust(2, '0')
 
         # IA doesn't handle leading hyphens,
         # so we use https://archive.org/details/youtubeannotations_64
         if index == "62"
           index = "64"
-          id = id.sub(/^-/, 'A')
+          video_id = video_id.sub(/^-/, 'A')
         end
 
-        file = URI.encode_www_form("#{id[0, 3]}/#{id}.xml")
+        file = URI.encode_www_form("#{video_id[0, 3]}/#{video_id}.xml")
 
-        location = make_client(INTERNET_ARCHIVE_URL, &.get("/download/youtubeannotations_#{index}/#{id[0, 2]}.tar/#{file}"))
+        location = make_client(INTERNET_ARCHIVE_URL, &.get("/download/youtubeannotations_#{index}/#{video_id[0, 2]}.tar/#{file}"))
 
         if !location.headers["Location"]?
           env.response.status_code = location.status_code
@@ -301,10 +301,10 @@ module Invidious::Routes::API::V1::Videos
 
         annotations = response.body
 
-        Helpers.cache_annotation(id, annotations)
+        Helpers.cache_annotation(video_id, annotations)
       end
     else # "youtube"
-      response = YT_POOL.client &.get("/annotations_invideo?video_id=#{id}")
+      response = YT_POOL.client &.get("/annotations_invideo?video_id=#{video_id}")
 
       if response.status_code != 200
         haltf env, response.status_code