diff --git a/src/ngircd/parse.c b/src/ngircd/parse.c
index d7dbffc2..c2603918 100644
--- a/src/ngircd/parse.c
+++ b/src/ngircd/parse.c
@@ -280,7 +280,7 @@ Validate_Prefix( CONN_ID Idx, REQUEST *Req, bool *Closed )
 	assert( client != NULL );
 
 	if (!Req->prefix && Client_Type(client) == CLIENT_SERVER
-	    && !Conn_Options(Idx) & CONN_RFC1459
+	    && !(Conn_Options(Idx) & CONN_RFC1459)
 	    && strcasecmp(Req->command, "ERROR") != 0
 	    && strcasecmp(Req->command, "PING") != 0)
 	{