diff --git a/eval_error.c b/eval_error.c
index 809d8aef000866..89e27afe56e728 100644
--- a/eval_error.c
+++ b/eval_error.c
@@ -309,9 +309,9 @@ rb_error_write(VALUE errinfo, VALUE emesg, VALUE errat, VALUE str, VALUE highlig
 	errat = Qnil;
     }
     eclass = CLASS_OF(errinfo);
-    if (NIL_P(reverse) || NIL_P(highlight)) {
+    if (NIL_P(reverse)) reverse = Qfalse;
+    if (NIL_P(highlight)) {
 	VALUE tty = (VALUE)rb_stderr_tty_p();
-	if (NIL_P(reverse)) reverse = tty;
 	if (NIL_P(highlight)) highlight = tty;
     }
     if (reverse) {
diff --git a/test/ruby/test_exception.rb b/test/ruby/test_exception.rb
index 9d7ffd882559b0..9529fc80133c66 100644
--- a/test/ruby/test_exception.rb
+++ b/test/ruby/test_exception.rb
@@ -1156,13 +1156,11 @@ def test_full_message
     if Exception.to_tty?
       assert_match(/\e/, message)
       message = message.gsub(/\e\[[\d;]*m/, '')
-      assert_operator(message, :start_with?, remark)
-      assert_operator(message, :end_with?, bottom)
     else
       assert_not_match(/\e/, message)
-      assert_operator(message, :start_with?, bottom)
-      assert_operator(message, :end_with?, top)
     end
+    assert_operator(message, :start_with?, bottom)
+    assert_operator(message, :end_with?, top)
   end
 
   def test_exception_in_message