diff --git a/cabal.project b/cabal.project
index be54576..a237a6b 100644
--- a/cabal.project
+++ b/cabal.project
@@ -5,4 +5,4 @@ packages:
 source-repository-package
   type: git
   location: https://git.rhiannon.website/rhi/svg-builder
-  tag: 1cbcd594d3009f9fd71f253b52ac82673bf5482e
+  tag: 39bb6a4e04ec2caccc23576b062ebfa0566bfb96
diff --git a/laantas-script/laantas-script.cabal b/laantas-script/laantas-script.cabal
index 433b83d..b150042 100644
--- a/laantas-script/laantas-script.cabal
+++ b/laantas-script/laantas-script.cabal
@@ -30,12 +30,12 @@ executable laantas-script
     RecordWildCards,
     ViewPatterns
   build-depends:
-    base >= 4.14.0.0 && < 4.17,
+    base >= 4.14.0.0 && < 4.20,
     containers ^>= 0.6.2.1,
     mtl ^>= 2.2.2,
     svg-builder ^>= 0.1.1,
     optparse-applicative ^>= 0.16.0.0,
-    text ^>= 1.2.3.2,
-    megaparsec ^>= 9.0.1
+    text ^>= 2.1,
+    megaparsec ^>= 9.6.1
   ghc-options:
     -Wall -threaded -rtsopts -with-rtsopts=-N
diff --git a/langfilter/Ebnf.hs b/langfilter/Ebnf.hs
index 41ed72e..5a83209 100644
--- a/langfilter/Ebnf.hs
+++ b/langfilter/Ebnf.hs
@@ -10,21 +10,23 @@ import Text.Pandoc.Definition
 import Data.Text (Text)
 import qualified Data.Text as Text
 import Data.Void
+import Data.List.NonEmpty (NonEmpty (..))
+import qualified Data.List.NonEmpty as NonEmpty
 
 data Rule =
     Rule Text Def
   | RCom Text -- ^ @(* comment *)@
   deriving (Eq, Show)
 data Def =
-    N Text      -- ^ @nonterminal@
-  | T Text      -- ^ @\'terminal\'@ or @\"terminal\"@
-  | S Text      -- ^ @?special?@
-  | Or [Def]    -- ^ choice @a | b | c@
-  | Seq [Def]   -- ^ sequence @a, b, c@
-  | Sub Def Def -- ^ difference @a - b@
-  | Opt Def     -- ^ opt @[a]@
-  | Many Def    -- ^ repetition @{a}@
-  | Com Text    -- ^ comment
+    N Text             -- ^ @nonterminal@
+  | T Text             -- ^ @\'terminal\'@ or @\"terminal\"@
+  | S Text             -- ^ @?special?@
+  | Or  (NonEmpty Def) -- ^ choice @a | b | c@
+  | Seq (NonEmpty Def) -- ^ sequence @a, b, c@
+  | Sub Def Def        -- ^ difference @a - b@
+  | Opt Def            -- ^ opt @[a]@
+  | Many Def           -- ^ repetition @{a}@
+  | Com Text           -- ^ comment
   deriving (Eq, Show)
 
 
@@ -51,9 +53,9 @@ render1 (RCom txt) =
 render1 (Rule name def) =
   row' [span "ebnf-nt" name] "=" d : map (row' [] "|") ds
  where
-  d:ds = splitOrs def
+  d :| ds = splitOrs def
   splitOrs (Or ds) = ds
-  splitOrs d       = [d]
+  splitOrs d       = NonEmpty.singleton d
   row' c1 p d = Row mempty [cell c1, cell [punc p], cell (renderDef d)]
   cell is = Cell mempty AlignDefault (RowSpan 1) (ColSpan 1) [Plain is]
 
@@ -76,9 +78,9 @@ renderDefAt p = \case
   T txt -> [span "ebnf-t" txt]
   S txt -> [span "ebnf-s" txt]
   Or ds -> renderParens (p > OR) $
-    intercalate [Space, punc "|", Space] $ renderDefAt OR <$> ds
+    intercalate [Space, punc "|", Space] $ renderDefAt OR <$> NonEmpty.toList ds
   Seq ds -> renderParens (p > SEQ) $
-    intercalate [punc ",", Space] $ renderDefAt SEQ <$> ds
+    intercalate [punc ",", Space] $ renderDefAt SEQ <$> NonEmpty.toList ds
   Sub d e -> renderParens (p >= SUB) $
     renderDefAt SUB d <>
     [Space, span "ebnf-sub" "−", Space] <>
@@ -111,10 +113,13 @@ def :: P Def
 def = ors
 
 ors :: P Def
-ors = list Or <$> seqs `sepBy1` (sym "|")
+ors = list1 Or <$> seqs `sepBy1'` (sym "|")
 
 seqs :: P Def
-seqs = list Seq <$> sub `sepBy1` (sym ",")
+seqs = list1 Seq <$> sub `sepBy1'` (sym ",")
+
+sepBy1' :: P a -> P z -> P (NonEmpty a)
+sepBy1' a b = NonEmpty.fromList <$> sepBy1 a b
 
 sub :: P Def
 sub = do
@@ -154,9 +159,9 @@ comment = do try (string_ "(*"); go ["(*"] 1 where
 bracketed :: (Def -> a) -> Char -> Char -> P a
 bracketed f o c = f <$> between (char' o) (char' c) def
 
-list :: ([a] -> a) -> [a] -> a
-list _ [x] = x
-list f xs  = f xs
+list1 :: (NonEmpty a -> a) -> NonEmpty a -> a
+list1 _ (x :| []) = x
+list1 f xs        = f xs
 
 
 sym :: Text -> P Text
diff --git a/langfilter/langfilter.cabal b/langfilter/langfilter.cabal
index 70ac7c4..f13767c 100644
--- a/langfilter/langfilter.cabal
+++ b/langfilter/langfilter.cabal
@@ -33,11 +33,11 @@ executable langfilter
     RecordWildCards,
     ViewPatterns
   build-depends:
-    base >= 4.14.0.0 && < 4.17,
+    base >= 4.14.0.0 && < 4.20,
     containers ^>= 0.6.2.1,
     filepath ^>= 1.4.2.1,
-    megaparsec ^>= 9.0.1,
+    megaparsec ^>= 9.6.1,
     process ^>= 1.6.11.0,
     pandoc-types ^>= 1.23,
-    text,
+    text ^>= 2.1,
     pretty-show ^>= 1.10