diff --git a/server/szurubooru/api/post_api.py b/server/szurubooru/api/post_api.py
index 090f03e5..fa3643a0 100644
--- a/server/szurubooru/api/post_api.py
+++ b/server/szurubooru/api/post_api.py
@@ -76,6 +76,7 @@ def create_post(
     flags = ctx.get_param_as_string_list(
         "flags", default=posts.get_default_flags(content)
     )
+    file_last_modified_time = ctx.get_param_as_int("fileLastModifiedTime")
 
     post, new_tags = posts.create_post(
         content, tag_names, None if anonymous else ctx.user
@@ -87,6 +88,7 @@ def create_post(
     posts.update_post_relations(post, relations)
     posts.update_post_notes(post, notes)
     posts.update_post_flags(post, flags)
+    posts.update_post_file_last_modified_time(post, file_last_modified_time)
     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 4efac774..ec58116c 100644
--- a/server/szurubooru/func/posts.py
+++ b/server/szurubooru/func/posts.py
@@ -427,9 +427,10 @@ def create_post(
 
 
 def update_post_file_last_modified_time(post: model.Post, timestamp: int) -> None:
-    assert post    
-    file_last_modified_time = datetime.fromtimestamp(ctx.get_param_as_int("lastModified", default=time.time()))
-    post.file_last_modified_time = file_last_modified_time
+    assert post
+    
+    # Timestamp is in ms, so it must be divided by 1000 otherwise out of range
+    post.file_last_modified_time = datetime.fromtimestamp(timestamp / 1000)
 
 def update_post_safety(post: model.Post, safety: str) -> None:
     assert post