diff --git a/array.c b/array.c
index e21c01194c..1eb1d2ea35 100644
--- a/array.c
+++ b/array.c
@@ -1781,8 +1781,8 @@ rb_ary_insert(int argc, VALUE *argv, VALUE ary)
 
     rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
     rb_ary_modify_check(ary);
-    if (argc == 1) return ary;
     pos = NUM2LONG(argv[0]);
+    if (argc == 1) return ary;
     if (pos == -1) {
 	pos = RARRAY_LEN(ary);
     }
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index d797ee8164..60938937cd 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -2121,6 +2121,7 @@ class TestArray < Test::Unit::TestCase
     assert_equal([0], a.insert(1))
     assert_equal([0, 1], a.insert(1, 1))
     assert_raise(ArgumentError) { a.insert }
+    assert_raise(TypeError) { a.insert(Object.new) }
     assert_equal([0, 1, 2], a.insert(-1, 2))
     assert_equal([0, 1, 3, 2], a.insert(-2, 3))
     assert_raise(RuntimeError) { [0].freeze.insert(0)}