diff --git a/ast.c b/ast.c
index 2ae738f7aa..ead4344be9 100644
--- a/ast.c
+++ b/ast.c
@@ -96,7 +96,7 @@ rb_ast_parse_str(VALUE str)
 {
     rb_ast_t *ast = 0;
 
-    str = rb_check_string_type(str);
+    StringValue(str);
     ast = rb_parser_compile_string_path(ast_parse_new(), Qnil, str, 1);
     return ast_parse_done(ast);
 }
diff --git a/test/ruby/test_ast.rb b/test/ruby/test_ast.rb
index ed4bcb37c0..d57b60b3f7 100644
--- a/test/ruby/test_ast.rb
+++ b/test/ruby/test_ast.rb
@@ -134,6 +134,14 @@ class TestAst < Test::Unit::TestCase
     assert_raise(TypeError) {RubyVM::AbstractSyntaxTree::Node.allocate}
   end
 
+  def test_parse_argument_error
+    assert_raise(TypeError) {RubyVM::AbstractSyntaxTree.parse(0)}
+    assert_raise(TypeError) {RubyVM::AbstractSyntaxTree.parse(nil)}
+    assert_raise(TypeError) {RubyVM::AbstractSyntaxTree.parse(false)}
+    assert_raise(TypeError) {RubyVM::AbstractSyntaxTree.parse(true)}
+    assert_raise(TypeError) {RubyVM::AbstractSyntaxTree.parse(:foo)}
+  end
+
   def test_column_with_long_heredoc_identifier
     term = "A"*257
     ast = RubyVM::AbstractSyntaxTree.parse("<<-#{term}\n""ddddddd\n#{term}\n")