diff --git a/app/lib/activitypub/activity/create.rb b/app/lib/activitypub/activity/create.rb
index 487e8e91e68a76..00f0dd42d7ba38 100644
--- a/app/lib/activitypub/activity/create.rb
+++ b/app/lib/activitypub/activity/create.rb
@@ -370,7 +370,7 @@ def name_language_map?
   end
 
   def unsupported_media_type?(mime_type)
-    mime_type.present? && !(MediaAttachment::IMAGE_MIME_TYPES + MediaAttachment::VIDEO_MIME_TYPES).include?(mime_type)
+    mime_type.present? && !MediaAttachment.supported_mime_types.include?(mime_type)
   end
 
   def supported_blurhash?(blurhash)
diff --git a/app/models/media_attachment.rb b/app/models/media_attachment.rb
index da375f6609c8a6..75a877d6117e2b 100644
--- a/app/models/media_attachment.rb
+++ b/app/models/media_attachment.rb
@@ -177,6 +177,14 @@ def focus
   before_save :set_meta
 
   class << self
+    def supported_mime_types
+      IMAGE_MIME_TYPES + VIDEO_MIME_TYPES + AUDIO_MIME_TYPES
+    end
+
+    def supported_file_extensions
+      IMAGE_FILE_EXTENSIONS + VIDEO_FILE_EXTENSIONS + AUDIO_FILE_EXTENSIONS
+    end
+
     private
 
     def file_styles(f)
diff --git a/app/serializers/initial_state_serializer.rb b/app/serializers/initial_state_serializer.rb
index e2d3a319049fbe..95a975618240ca 100644
--- a/app/serializers/initial_state_serializer.rb
+++ b/app/serializers/initial_state_serializer.rb
@@ -65,7 +65,7 @@ def accounts
   end
 
   def media_attachments
-    { accept_content_types: MediaAttachment::IMAGE_FILE_EXTENSIONS + MediaAttachment::VIDEO_FILE_EXTENSIONS + MediaAttachment::AUDIO_FILE_EXTENSIONS + MediaAttachment::IMAGE_MIME_TYPES + MediaAttachment::VIDEO_MIME_TYPES + MediaAttachment::AUDIO_MIME_TYPES }
+    { accept_content_types: MediaAttachment.supported_file_extensions + MediaAttachment.supported_mime_types }
   end
 
   private