diff --git a/interpreter/dune-project b/interpreter/dune-project
index 8392b339..4c048f55 100644
--- a/interpreter/dune-project
+++ b/interpreter/dune-project
@@ -7,9 +7,7 @@
 (implicit_transitive_deps false)
 
 (license Apache-2.0)
-
-(source
-  (github WebAssembly/spec))
+(source (github WebAssembly/spec))
 
 (authors "Andreas Rossberg <rossberg@mpi-sws.org")
 (maintainers "Andreas Rossberg <rossberg@mpi-sws.org")
@@ -20,4 +18,6 @@
   (tags (wasm webassembly spec interpreter))
   (depends
     (ocaml (>= 4.12))
-    (menhir (>= 20220210))))
+    (menhir (>= 20220210))
+  )
+)
diff --git a/interpreter/text/parser.mly b/interpreter/text/parser.mly
index 3747df89..71ee2a92 100644
--- a/interpreter/text/parser.mly
+++ b/interpreter/text/parser.mly
@@ -375,8 +375,8 @@ val_type :
   | ref_type { fun c -> RefT ($1 c) }
 
 val_type_list :
-  | /* empty */ { 0l, fun c -> [] }
-  | val_type val_type_list { I32.add (fst $2) 1l, fun c -> $1 c :: snd $2 c }
+  | list(val_type)
+    { Lib.List32.length $1, fun c -> List.map (fun f -> f c) $1 }
 
 global_type :
   | val_type { fun c -> GlobalT (Cons, $1 c) }