diff --git a/src/Data/GS1/DWhat.hs b/src/Data/GS1/DWhat.hs
index e3244e8..7be5c0a 100644
--- a/src/Data/GS1/DWhat.hs
+++ b/src/Data/GS1/DWhat.hs
@@ -288,4 +288,4 @@ instance ToJSON DWhat where
   toJSON (TransactWhat o)    = toJSON o
   toJSON (TransformWhat o)   = toJSON o
   toJSON (AssociationWhat o) = toJSON o
-  
+
diff --git a/stack.yaml.lock b/stack.yaml.lock
new file mode 100644
index 0000000..373e614
--- /dev/null
+++ b/stack.yaml.lock
@@ -0,0 +1,12 @@
+# This file was autogenerated by Stack.
+# You should not edit this file by hand.
+# For more information, please see the documentation at:
+#   https://docs.haskellstack.org/en/stable/lock_files
+
+packages: []
+snapshots:
+- completed:
+    size: 498398
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/13/23.yaml
+    sha256: 63151ca76f39d5cfbd266ce019236459fdda53fbefd2200aedeb33bcc81f808e
+  original: lts-13.23