diff --git a/crud.py b/crud.py
index aeb78d0..d708e93 100644
--- a/crud.py
+++ b/crud.py
@@ -5,6 +5,7 @@ from lnbits.helpers import urlsafe_short_hash
 
 from . import db  # , maindb
 from .models import CreatePayLinkData, PayLink
+from .services import check_lnaddress_format
 
 # from loguru import logger
 
@@ -15,9 +16,8 @@ async def check_lnaddress_update(username: str, id: str) -> bool:
         "SELECT username FROM lnurlp.pay_links WHERE username = ? AND id = ?",
         (username, id),
     )
-    if len(row) > 1:
-        assert False, "Username already exists. Try a different one."
-        return
+    if row:
+        raise Exception("Username already exists. Try a different one.")
     else:
         return True
 
@@ -28,19 +28,11 @@ async def check_lnaddress_not_exists(username: str) -> bool:
         "SELECT username FROM lnurlp.pay_links WHERE username = ?", (username,)
     )
     if row:
-        assert False, "Username already exists. Try a different one."
+        raise Exception("Username already exists. Try a different one.")
     else:
         return True
 
 
-async def check_lnaddress_format(username: str) -> bool:
-    # check username complies with lnaddress specification
-    if not re.match("^[a-z0-9-_.]{3,15}$", username):
-        assert False, "Only letters a-z0-9-_. allowed, min 3 and max 15 characters!"
-        return
-    return True
-
-
 async def create_pay_link(data: CreatePayLinkData, wallet_id: str) -> PayLink:
     if data.username:
         await check_lnaddress_format(data.username)