diff --git a/hledger-lib/Text/Megaparsec/Custom.hs b/hledger-lib/Text/Megaparsec/Custom.hs
index c19195836..6fd034cbc 100644
--- a/hledger-lib/Text/Megaparsec/Custom.hs
+++ b/hledger-lib/Text/Megaparsec/Custom.hs
@@ -12,7 +12,6 @@ module Text.Megaparsec.Custom (
   -- * Constructing custom parse errors
   parseErrorAt,
   parseErrorAtRegion,
-  withSource,
 
   -- * Pretty-printing custom parse errors
   customParseErrorPretty,
@@ -64,10 +63,6 @@ data CustomErr
   = ErrorFailAt SourcePos -- Starting position
                 Pos -- Ending position (column; same line as start)
                 String -- Error message
-  -- | Attach a source file to a parse error (for error reporting from
-  -- include files, e.g. with the 'region' parser combinator)
-  | ErrorWithSource Text -- Source file contents
-                    (ParseError Char CustomErr) -- The original
   deriving (Show, Eq, Ord)
 
 -- We require an 'Ord' instance for 'CustomError' so that they may be
@@ -79,7 +74,6 @@ deriving instance (Ord c, Ord e) => Ord (ParseError c e)
 
 instance ShowErrorComponent CustomErr where
   showErrorComponent (ErrorFailAt _ _ errMsg) = errMsg
-  showErrorComponent (ErrorWithSource _ e) = parseErrorTextPretty e
 
 
 --- * Constructing custom parse errors
@@ -107,13 +101,6 @@ parseErrorAtRegion startPos endPos msg =
                then endCol' else startCol
   in  ErrorFailAt startPos endCol msg
 
--- | Attach a source file to a parse error. Intended for use with the
--- 'region' parser combinator.
-
-withSource :: Text -> ParseError Char CustomErr -> ParseError Char CustomErr
-withSource s e =
-  FancyError (errorPos e) $ S.singleton $ ErrorCustom $ ErrorWithSource s e
-
 
 --- * Pretty-printing custom parse errors
 
@@ -127,9 +114,6 @@ customParseErrorPretty :: Text -> ParseError Char CustomErr -> String
 customParseErrorPretty source err = case findCustomError err of
   Nothing -> customParseErrorPretty' source err pos1
 
-  Just (ErrorWithSource customSource customErr) ->
-    customParseErrorPretty customSource customErr
-
   Just (ErrorFailAt sourcePos col errMsg) ->
     let newPositionStack = sourcePos NE.:| NE.tail (errorPos err)
         errorIntervalLength = mkPos $ max 1 $
@@ -200,6 +184,7 @@ data FinalParseErrorBundle' e = FinalParseErrorBundle'
 
 type FinalParseErrorBundle = FinalParseErrorBundle' CustomErr
 
+
 --- * Constructing and throwing final parse errors
 
 -- | Convert a "regular" parse error into a "final" parse error.
@@ -229,6 +214,7 @@ finalCustomFailure
   :: (MonadParsec e s m, MonadError (FinalParseError' e) m) => e -> m a
 finalCustomFailure = finalFancyFailure . S.singleton . ErrorCustom
 
+
 --- * Handling errors from include files with "final" parse errors
 
 -- Some care must be taken for sources to be attached to the right parse
@@ -268,6 +254,7 @@ attachSource filePath sourceText finalParseError =
       { sourceFileStack = filePath NE.<| sourceFileStack bundle
       }
 
+
 --- * Pretty-printing final parse errors
 
 -- | Pretty-print a "final" parse error: print the stack of include files,