diff --git a/lib/elixir/src/elixir_parser.yrl b/lib/elixir/src/elixir_parser.yrl
index 46119edbcb..e125000506 100644
--- a/lib/elixir/src/elixir_parser.yrl
+++ b/lib/elixir/src/elixir_parser.yrl
@@ -1,7 +1,6 @@
 Nonterminals
   grammar expr_list
-  expr container_expr block_expr access_expr
-  no_parens_expr no_parens_one_expr no_parens_one_ambig_expr 
+  expr container_expr block_expr no_parens_expr no_parens_one_expr access_expr
   bracket_expr bracket_at_expr bracket_arg matched_expr unmatched_expr max_expr
   op_expr matched_op_expr no_parens_op_expr
   comp_op_eol at_op_eol unary_op_eol and_op_eol or_op_eol capture_op_eol
@@ -16,9 +15,8 @@ Nonterminals
   assoc_op_eol assoc_expr assoc_base assoc_update assoc_update_kw assoc
   container_args_base container_args
   call_args_parens_expr call_args_parens_base call_args_parens parens_call
-  call_args_no_parens_one call_args_no_parens_one_ambig call_args_no_parens_expr
-  call_args_no_parens_comma_expr call_args_no_parens_all call_args_no_parens_many
-  call_args_no_parens_many_strict
+  call_args_no_parens_one call_args_no_parens_expr call_args_no_parens_comma_expr
+  call_args_no_parens_all call_args_no_parens_many call_args_no_parens_many_strict
   stab stab_eoe stab_expr stab_maybe_expr stab_parens_many
   kw_eol kw_base kw call_args_no_parens_kw_expr call_args_no_parens_kw
   dot_op dot_alias dot_identifier dot_op_identifier dot_do_identifier
@@ -88,29 +86,11 @@ expr_list -> expr_list eoe expr : ['$3'|'$1'].
 
 expr -> matched_expr : '$1'.
 expr -> no_parens_expr : '$1'.
-expr -> no_parens_one_ambig_expr : '$1'.
 expr -> unmatched_expr : '$1'.
 
 %% In Elixir we have three main call syntaxes: with parentheses,
 %% without parentheses and with do blocks. They are represented
 %% in the AST as matched, no_parens and unmatched.
-%% 
-%% Calls without parentheses are further divided according to how
-%% problematic they are:
-%%
-%% (a) no_parens: a call with several arguments (e.g. `f a, b`)
-%%
-%% (b) no_parens_one: a call with one unproblematic argument
-%%     (e.g. `f a` or `f g a` and similar)
-%%
-%% (c) no_parens_one_ambig: a call with one argument which is
-%%     itself a no_parens or no_parens_one_ambig (e.g. `f g a, b`
-%%     or `f g h a, b` and similar)
-%%
-%% Note, in particular, that no_parens_one_ambig expressions are
-%% ambiguous and are interpreted such that the outer function has
-%% arity 1 (e.g. `f g a, b` is interpreted as `f(g(a, b))` rather
-%% than `f(g(a), b)`). Hence the name, no_parens_one_ambig.
 %%
 %% The distinction is required because we can't, for example, have
 %% a function call with a do block as argument inside another do
@@ -212,9 +192,6 @@ no_parens_one_expr -> dot_identifier call_args_no_parens_one : build_identifier(
 no_parens_one_expr -> dot_do_identifier : build_identifier('$1', nil).
 no_parens_one_expr -> dot_identifier : build_identifier('$1', nil).
 
-no_parens_one_ambig_expr -> dot_op_identifier call_args_no_parens_one_ambig : build_identifier('$1', '$2').
-no_parens_one_ambig_expr -> dot_identifier call_args_no_parens_one_ambig : build_identifier('$1', '$2').
-
 %% From this point on, we just have constructs that can be
 %% used with the access syntax. Notice that (dot_)identifier
 %% is not included in this list simply because the tokenizer
@@ -430,22 +407,17 @@ parens_call -> matched_expr dot_call_op : {'.', meta('$2'), ['$1']}. % Fun/local
 % Function calls with no parentheses
 
 call_args_no_parens_expr -> matched_expr : '$1'.
-call_args_no_parens_expr -> no_parens_one_ambig_expr : '$1'.
 call_args_no_parens_expr -> no_parens_expr : throw_no_parens_many_strict('$1').
 
 call_args_no_parens_comma_expr -> matched_expr ',' call_args_no_parens_expr : ['$3', '$1'].
-call_args_no_parens_comma_expr -> no_parens_one_ambig_expr ',' call_args_no_parens_expr : ['$3', '$1'].
 call_args_no_parens_comma_expr -> call_args_no_parens_comma_expr ',' call_args_no_parens_expr : ['$3'|'$1'].
 
 call_args_no_parens_all -> call_args_no_parens_one : '$1'.
-call_args_no_parens_all -> call_args_no_parens_one_ambig : '$1'.
 call_args_no_parens_all -> call_args_no_parens_many : '$1'.
 
 call_args_no_parens_one -> call_args_no_parens_kw : ['$1'].
 call_args_no_parens_one -> matched_expr : ['$1'].
-
-call_args_no_parens_one_ambig -> no_parens_expr : ['$1'].
-call_args_no_parens_one_ambig -> no_parens_one_ambig_expr : ['$1'].
+call_args_no_parens_one -> no_parens_expr : ['$1'].
 
 call_args_no_parens_many -> matched_expr ',' call_args_no_parens_kw : ['$1', '$3'].
 call_args_no_parens_many -> call_args_no_parens_comma_expr : reverse('$1').
@@ -462,7 +434,6 @@ stab_parens_many -> open_paren call_args_no_parens_many close_paren : '$2'.
 
 container_expr -> matched_expr : '$1'.
 container_expr -> unmatched_expr : '$1'.
-container_expr -> no_parens_one_ambig_expr : throw_no_parens_many_strict('$1').
 container_expr -> no_parens_expr : throw_no_parens_many_strict('$1').
 
 container_args_base -> container_expr : ['$1'].
diff --git a/lib/elixir/test/elixir/kernel/errors_test.exs b/lib/elixir/test/elixir/kernel/errors_test.exs
index efce105b60..758e8af5d5 100644
--- a/lib/elixir/test/elixir/kernel/errors_test.exs
+++ b/lib/elixir/test/elixir/kernel/errors_test.exs
@@ -129,18 +129,15 @@ defmodule Kernel.ErrorsTest do
           "nested calls. Syntax error before: ','"
 
     assert_compile_fail SyntaxError, msg, '[foo 1, 2]'
-    assert_compile_fail SyntaxError, msg, '[foo bar 1, 2]'
     assert_compile_fail SyntaxError, msg, '[do: foo 1, 2]'
     assert_compile_fail SyntaxError, msg, 'foo(do: bar 1, 2)'
     assert_compile_fail SyntaxError, msg, '{foo 1, 2}'
-    assert_compile_fail SyntaxError, msg, '{foo bar 1, 2}'
     assert_compile_fail SyntaxError, msg, 'foo 1, foo 2, 3'
     assert_compile_fail SyntaxError, msg, 'foo(1, foo 2, 3)'
 
     assert is_list List.flatten [1]
     assert is_list Enum.reverse [3, 2, 1], [4, 5, 6]
     assert is_list(Enum.reverse [3, 2, 1], [4, 5, 6])
-    assert [List.flatten List.flatten [1]] == [[1]]
   end
 
   test :syntax_error_on_atom_dot_alias do