diff --git a/grammar/SIPGrammar.st b/grammar/SIPGrammar.st
index add34dc..5b468e6 100644
--- a/grammar/SIPGrammar.st
+++ b/grammar/SIPGrammar.st
@@ -90,8 +90,9 @@ PP.PPCompositeParser subclass: SIPGrammar [
 
     host [
         <category: 'generic'>
-        "TODO: too simplieified"
-        ^ (#letter asParser / (PP.PPPredicateObjectParser chars: '0123456789.-' message: 'host')) plus flatten
+        ^ (PP.PPPredicateObjectParser on: (PP.PPCharSetPredicate on:
+                                [:char | char isAlphaNumeric or: [
+                                    '.-' includes: char]]) message: 'host') plus flatten
     ]
 
     port [