diff --git a/src-extra/transformation/JbeamEdit/Transformation.hs b/src-extra/transformation/JbeamEdit/Transformation.hs
index b49574ca..c022ce2b 100644
--- a/src-extra/transformation/JbeamEdit/Transformation.hs
+++ b/src-extra/transformation/JbeamEdit/Transformation.hs
@@ -317,7 +317,7 @@ vertexForestToNodeVector initialMeta vf =
               oMap
 
       (_, listsOfNodes) = mapAccumL stepType initialMeta treesOrder
-   in V.fromList (concat listsOfNodes)
+   in foldMap V.fromList listsOfNodes
 
 treesOrder :: [VertexTreeType]
 treesOrder = [LeftTree, MiddleTree, RightTree, SupportTree]
diff --git a/src-extra/transformation/JbeamEdit/Transformation/BeamExtraction.hs b/src-extra/transformation/JbeamEdit/Transformation/BeamExtraction.hs
index 7e199f58..0c95705f 100644
--- a/src-extra/transformation/JbeamEdit/Transformation/BeamExtraction.hs
+++ b/src-extra/transformation/JbeamEdit/Transformation/BeamExtraction.hs
@@ -7,6 +7,8 @@ import Data.Map (Map)
 import Data.Map qualified as M
 import Data.Maybe (catMaybes)
 import Data.Ord (Down (Down))
+import Data.Set (Set)
+import Data.Set qualified as S
 import Data.Text (Text)
 import Data.Vector (Vector)
 import Data.Vector qualified as V
@@ -20,15 +22,14 @@ beamQuery :: NP.NodePath
 beamQuery = fromList [NP.ObjectIndex 0, NP.ObjectKey "beams"]
 
 rejectUnknownName
-  :: Foldable t
-  => t Text
+  :: Set Text
   -> Maybe (Vector Text)
   -> Maybe (Vector Text)
 rejectUnknownName knownNodeNames maybeBeam =
   bool
     maybeBeam
     Nothing
-    (any (any (`notElem` knownNodeNames)) maybeBeam)
+    (any (any (`S.notMember` knownNodeNames)) maybeBeam)
 
 possiblyBeam :: Node -> Either Node (Maybe (Vector Text))
 possiblyBeam node
@@ -53,7 +54,7 @@ vertexConns
 vertexConns maxSupport topNode vsPerType =
   go <$> extractBeams topNode
   where
-    knownNodeNames = concatMap (map anVertexName) vsPerType
+    knownNodeNames = foldMap (foldr (S.insert . anVertexName) mempty) vsPerType
     go beams =
       let possiblyInnerBeam = (:) . fmap (rejectUnknownName knownNodeNames) . possiblyBeam
           (badNodes, beamPairs) =
diff --git a/src/JbeamEdit/Core/Node.hs b/src/JbeamEdit/Core/Node.hs
index dca96190..8a7e0bbd 100644
--- a/src/JbeamEdit/Core/Node.hs
+++ b/src/JbeamEdit/Core/Node.hs
@@ -121,7 +121,7 @@ possiblyChildren n = expectArray n <|> expectObject n
 
 moreNodesThanOne :: Vector Node -> Bool
 moreNodesThanOne v
-  | len == 1 = any moreNodesThanOne . possiblyChildren $ V.head v
+  | len == 1 = any moreNodesThanOne . possiblyChildren $ V.unsafeHead v
   | len > 1 = True
   | otherwise = False
   where
diff --git a/src/JbeamEdit/Formatting.hs b/src/JbeamEdit/Formatting.hs
index 22c22a95..bb87eac7 100644
--- a/src/JbeamEdit/Formatting.hs
+++ b/src/JbeamEdit/Formatting.hs
@@ -128,11 +128,10 @@ applyIndentation n s
   | otherwise = T.replicate n " " <> s
 
 skipHeaderRow :: Vector (Vector Node) -> Vector (Vector Node)
-skipHeaderRow nodes =
-  case V.uncons nodes of
-    Just (headerRow, rest) ->
-      bool nodes rest (all isStringNode headerRow)
-    Nothing -> nodes
+skipHeaderRow nodes
+  | V.length nodes > 1 =
+      bool nodes (V.unsafeTail nodes) (all isStringNode $ V.unsafeHead nodes)
+  | otherwise = nodes
 
 maxColumnLengths
   :: RuleSet -> NC.NodeCursor -> Vector (Vector Node) -> Vector Int