diff --git a/src/sbbs3/newuser.cpp b/src/sbbs3/newuser.cpp
index 4effc876c5f0cfb28b12a8653313fb4da8318dd7..7dfee39aa9ee5ce99c1cad42924a60f739b0501a 100644
--- a/src/sbbs3/newuser.cpp
+++ b/src/sbbs3/newuser.cpp
@@ -197,6 +197,7 @@ BOOL sbbs_t::newuser()
 				getstr(useron.alias,LEN_ALIAS,kmode);
 				truncsp(useron.alias);
 				if(useron.alias[0]<=SP || !isalpha(useron.alias[0])
+					|| alias(&cfg,useron.alias,tmp)!=useron.alias
 					|| !stricmp(useron.alias,cfg.sys_id)
 					|| strchr(useron.alias,0xff)
 					|| matchuser(&cfg,useron.alias,TRUE /* sysop_alias */)