diff --git a/app/Gyehoek/Sexp.hs b/app/Gyehoek/Sexp.hs
index 5c25a6f..0ff2ba8 100644
--- a/app/Gyehoek/Sexp.hs
+++ b/app/Gyehoek/Sexp.hs
@@ -52,8 +52,8 @@ parseSexps f = marshal . SexpLoc.parseSexps f . view lazy . encodeUtf8
 
 nonEmptyGrammar :: Grammar p (NonEmpty x :- t) (List x :- x :- t)
 nonEmptyGrammar = IGB.Iso
-  (\((x:|xs) :- t) -> xs :- x :- t)
-  (\(xs :- x :- t) -> (x:|xs) :- t)
+  (\((x:|xs) :- t) -> reverse xs :- x :- t)
+  (\(xs :- x :- t) -> (x :| reverse xs) :- t)
 
 nonempty :: SexpGrammar a -> SexpGrammar (NonEmpty a)
 nonempty a =
diff --git a/play/t.anf b/play/t.anf
index 6102161..2ab7790 100644
--- a/play/t.anf
+++ b/play/t.anf
@@ -1,4 +1,4 @@
 ;;; -*- mode:scheme -*-
 
-(let ((x0 (prim:cons 4 2)) (x3 (prim:write x2)) (x2 (prim:* 3 x1)) (x1 (prim:cdr x0))) x3)
+(let ((x0 (prim:cons 4 2)) (x1 (prim:cdr x0)) (x2 (prim:* 3 x1)) (x3 (prim:write x2))) x3)