diff --git a/src/exabgp/bgp/message/update/attribute/sr/prefixsid.py b/src/exabgp/bgp/message/update/attribute/sr/prefixsid.py
index 1323c99a2..be1e05a7e 100644
--- a/src/exabgp/bgp/message/update/attribute/sr/prefixsid.py
+++ b/src/exabgp/bgp/message/update/attribute/sr/prefixsid.py
@@ -21,7 +21,7 @@
 @Attribute.register()
 class PrefixSid(Attribute):
     ID = Attribute.CODE.BGP_PREFIX_SID
-    FLAG = FLAG = Attribute.Flag.TRANSITIVE | Attribute.Flag.OPTIONAL
+    FLAG = Attribute.Flag.TRANSITIVE | Attribute.Flag.OPTIONAL
     CACHING = True
     TLV = -1