diff --git a/core/thread.py b/core/thread.py
index b8f28d129b..bf77425b59 100644
--- a/core/thread.py
+++ b/core/thread.py
@@ -1001,7 +1001,7 @@ async def send(
                 attachments.append(attachment)
 
         image_urls = re.findall(
-            r"http[s]?:\/\/(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*(),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+",
+            r"http[s]?:\/\/(?:[a-zA-Z]|[0-9]|[$\-_@.&+]|[!*(),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+",
             message.content,
         )