diff --git a/src/elf_section_header_table.lem b/src/elf_section_header_table.lem
index bf808c1..6661d16 100644
--- a/src/elf_section_header_table.lem
+++ b/src/elf_section_header_table.lem
@@ -638,7 +638,7 @@ let rec read_elf32_section_header_table' endian bs0 =
   else
     read_elf32_section_header_table_entry endian bs0 >>= fun (entry, bs1) ->
     read_elf32_section_header_table' endian bs1 >>= fun sht ->
-    return (sht ++ [entry])
+    return (entry :: sht)
 
 (** [read_elf64_section_header_table' ed bs0] parses an ELF64 section header table
   * from byte sequence [bs0] assuming endianness [ed].  Assumes [bs0] is of the
@@ -653,7 +653,7 @@ let rec read_elf64_section_header_table' endian bs0 =
   else
     read_elf64_section_header_table_entry endian bs0 >>= fun (entry, bs1) ->
     read_elf64_section_header_table' endian bs1 >>= fun sht ->
-    return (sht ++ [entry])
+    return (entry :: sht)
 
 (** [read_elf32_section_header_table sz ed bs0] parses an ELF32 section header
   * table from a [sz] sized prefix of byte sequence [bs0] assuming endianness
diff --git a/src/error.lem b/src/error.lem
index 90f946b..b75df28 100644
--- a/src/error.lem
+++ b/src/error.lem
@@ -86,14 +86,14 @@ let rec repeatM' count seed action =
     action seed >>= fun (head, seed) ->
     repeatM' (count - 1) seed action >>= fun (tail, seed) ->
     return (head::tail, seed)
-	
+
 (** [mapM f xs] maps [f] across [xs], failing if [f] fails on any element of [xs].
   *)
 val mapM' : forall 'a 'b. ('a -> error 'b) -> list 'a -> error (list 'b) -> error (list 'b)
-let rec mapM' f xs acc =
+let rec mapM' f xs rev_acc =
 	match xs with
-		| []    -> acc
-		| x::xs -> mapM' f xs (acc >>= fun tl -> f x >>= fun hd -> return (hd::tl))
+		| []    -> rev_acc >>= fun rev_acc -> return (List.reverse rev_acc)
+		| x::xs -> mapM' f xs (rev_acc >>= fun tl -> f x >>= fun hd -> return (hd::tl))
 	end
 
 val mapM : forall 'a 'b. ('a -> error 'b) -> list 'a -> error (list 'b)