diff --git a/Data/Tagset/Positional.hs b/Data/Tagset/Positional.hs
--- a/Data/Tagset/Positional.hs
+++ b/Data/Tagset/Positional.hs
@@ -189,7 +189,7 @@
 lineSpaces = many lineSpace
 
 ident :: Parser String
-ident = many1 $ oneOf $ ['a'..'z'] ++ ['A'..'Z'] ++ ['0'..'9'] ++ "."
+ident = many1 $ oneOf $ ['a'..'z'] ++ ['A'..'Z'] ++ ['0'..'9'] ++ "." ++ "_"
 
 secName :: String -> Parser Char
 secName name = char '[' *> string name *> char ']'
diff --git a/tagset-positional.cabal b/tagset-positional.cabal
--- a/tagset-positional.cabal
+++ b/tagset-positional.cabal
@@ -1,5 +1,5 @@
 name:               tagset-positional
-version:            0.3.0
+version:            0.3.1
 synopsis:           Positional tags and tagsets
 description:
     The library provides printing and parsing functions for positional
@@ -22,7 +22,7 @@
       , parsec
       , text
       , binary
-      , text-binary >= 0.1 && < 0.2
+      , text-binary
 
     exposed-modules:
         Data.Tagset.Positional