diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,11 @@
+## 0.7.3.0
+
+- Expose parser error position details
+
+## 0.7.2.0
+
+- '|json' filter
+
 ## 0.7.1.0
 
 - `StripBlocks` and `LTrimBlocks` options
diff --git a/ginger.cabal b/ginger.cabal
--- a/ginger.cabal
+++ b/ginger.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                ginger
-version:             0.7.2.0
+version:             0.7.3.0
 synopsis:            An implementation of the Jinja2 template language in Haskell
 description:         Ginger is Jinja, minus the most blatant pythonisms. Wants
                      to be feature complete, but isn't quite there yet.
diff --git a/src/Text/Ginger/Parse.hs b/src/Text/Ginger/Parse.hs
--- a/src/Text/Ginger/Parse.hs
+++ b/src/Text/Ginger/Parse.hs
@@ -16,19 +16,21 @@
 , formatParserError
 , IncludeResolver
 , Source, SourceName
-, SourcePos
+, SourcePos (..)
+, sourceName
 , sourceLine
 , sourceColumn
-, sourceName
+, setSourceName
 )
 where
 
-import Text.Parsec ( ParseError
-                   , SourcePos
+import Text.Parsec ( ParseError (..)
+                   , SourcePos (..)
                    , SourceName (..)
+                   , sourceName
                    , sourceLine
                    , sourceColumn
-                   , sourceName
+                   , setSourceName
                    , ParsecT
                    , runParserT
                    , try, lookAhead
diff --git a/src/Text/Ginger/Run/Builtins.hs b/src/Text/Ginger/Run/Builtins.hs
--- a/src/Text/Ginger/Run/Builtins.hs
+++ b/src/Text/Ginger/Run/Builtins.hs
@@ -298,6 +298,8 @@
                 (\(key, value) -> (key,) <$> mapFunction [(Nothing, value)])
         (Nothing, Just items) ->
             toGVal <$> mapM (mapFunction . (:[]) . (Nothing,)) items
+        (Nothing, Nothing) ->
+            return def
             
 
 gfnSort :: Monad m => Function (Run p m h)