diff --git a/prettyprinter/src/Data/Text/Prettyprint/Doc/Internal.hs b/prettyprinter/src/Data/Text/Prettyprint/Doc/Internal.hs
index 9c966c25..3f30c1ea 100755
--- a/prettyprinter/src/Data/Text/Prettyprint/Doc/Internal.hs
+++ b/prettyprinter/src/Data/Text/Prettyprint/Doc/Internal.hs
@@ -553,7 +553,7 @@ changesUponFlattening :: Doc ann -> Maybe (Doc ann)
 changesUponFlattening = \doc -> case doc of
     FlatAlt _ y     -> Just (flatten y)
     Line            -> Just Fail
-    Union x _       -> changesUponFlattening x <|> Just x
+    Union x _       -> Just x
     Nest i x        -> fmap (Nest i) (changesUponFlattening x)
     Annotated ann x -> fmap (Annotated ann) (changesUponFlattening x)