diff --git a/server/szurubooru/api/post_api.py b/server/szurubooru/api/post_api.py
index 84094845..09aea90a 100644
--- a/server/szurubooru/api/post_api.py
+++ b/server/szurubooru/api/post_api.py
@@ -54,7 +54,9 @@ def create_post(
         source = ctx.get_param_as_string('contentUrl', default='')
     relations = ctx.get_param_as_int_list('relations', default=[])
     notes = ctx.get_param_as_list('notes', default=[])
-    flags = ctx.get_param_as_string_list('flags', default=[])
+    flags = ctx.get_param_as_string_list(
+        'flags',
+        default=posts.get_default_flags(content))
 
     post, new_tags = posts.create_post(
         content, tag_names, None if anonymous else ctx.user)
@@ -65,7 +67,6 @@ def create_post(
     posts.update_post_relations(post, relations)
     posts.update_post_notes(post, notes)
     posts.update_post_flags(post, flags)
-    posts.test_sound(post, content)
     if ctx.has_file('thumbnail'):
         posts.update_post_thumbnail(post, ctx.get_file('thumbnail'))
     ctx.session.add(post)
diff --git a/server/szurubooru/func/posts.py b/server/szurubooru/func/posts.py
index 0f2cb51c..f0224b40 100644
--- a/server/szurubooru/func/posts.py
+++ b/server/szurubooru/func/posts.py
@@ -467,15 +467,14 @@ def generate_alternate_formats(post: model.Post, content: bytes) \
     return new_posts
 
 
-def test_sound(post: model.Post, content: bytes) -> None:
-    assert post
+def get_default_flags(content: bytes) -> List[str]:
     assert content
+    ret = []
     if mime.is_video(mime.get_mime_type(content)):
+        ret.append(model.Post.FLAG_LOOP)
         if images.Image(content).check_for_sound():
-            flags = post.flags
-            if model.Post.FLAG_SOUND not in flags:
-                flags.append(model.Post.FLAG_SOUND)
-            update_post_flags(post, flags)
+            ret.append(model.Post.FLAG_SOUND)
+    return ret
 
 
 def purge_post_signature(post: model.Post) -> None: