diff --git a/ent/internal/preparser/grammar.peg b/ent/internal/preparser/grammar.peg
index fcddecf..e321885 100644
--- a/ent/internal/preparser/grammar.peg
+++ b/ent/internal/preparser/grammar.peg
@@ -41,7 +41,7 @@ _ <- MultipleSpace / SingleSpace
 
 NotLetterOrEnd <- NotLetter / END
 
-NotLetter <- [[^A-Z0-9_\-]]
+NotLetter <- [[^A-Z0-9_\-\.]]
 
 MultipleSpace <- SingleSpace SingleSpace+