diff --git a/app/Builtins.hs b/app/Builtins.hs
index 34cc665..a273660 100644
--- a/app/Builtins.hs
+++ b/app/Builtins.hs
@@ -274,12 +274,12 @@ modDef :: ([Code] -> Maybe [Code]) -> IR.Id -> PrlgEnv ()
 modDef fn struct =
   modify $ \s -> s {defs = M.alter (maybe (fn []) fn) struct $ defs s}
 
-addClauseZ :: Code -> IR.Id -> PrlgEnv ()
-addClauseZ code = modDef $ Just . ([code] ++)
-
 addClauseA :: Code -> IR.Id -> PrlgEnv ()
 addClauseA code = modDef $ Just . (code :)
 
+addClauseZ :: Code -> IR.Id -> PrlgEnv ()
+addClauseZ code = modDef $ Just . (++ [code])
+
 addProcedure :: [Code] -> IR.Id -> PrlgEnv ()
 addProcedure heads = modDef $ Just . const heads