diff --git a/error.c b/error.c
index 058446d60b..ba6f1ea689 100644
--- a/error.c
+++ b/error.c
@@ -348,11 +348,11 @@ warning_write(int argc, VALUE *argv, VALUE buf)
 static VALUE
 rb_warn_m(int argc, VALUE *argv, VALUE exc)
 {
-    VALUE opts, uplevel = Qnil;
+    VALUE opts, location = Qnil;
 
     if (!NIL_P(ruby_verbose) && argc > 0 &&
 	    (argc = rb_scan_args(argc, argv, "*:", NULL, &opts)) > 0) {
-	VALUE str = argv[0];
+	VALUE str = argv[0], uplevel = Qnil;
 	if (!NIL_P(opts)) {
 	    static ID kwds[1];
 	    if (!kwds[0]) {
@@ -370,22 +370,25 @@ rb_warn_m(int argc, VALUE *argv, VALUE exc)
 		}
 		args[0] = LONG2NUM(lev + 1);
 		args[1] = INT2FIX(1);
-		uplevel = rb_vm_thread_backtrace_locations(2, args, GET_THREAD()->self);
+		location = rb_vm_thread_backtrace_locations(2, args, GET_THREAD()->self);
 		if (!NIL_P(uplevel)) {
-		    uplevel = rb_ary_entry(uplevel, 0);
+		    location = rb_ary_entry(location, 0);
 		}
 	    }
 	}
 	if (argc > 1 || !NIL_P(uplevel) || !end_with_asciichar(str, '\n')) {
+	    VALUE path;
 	    if (NIL_P(uplevel)) {
 		str = rb_str_tmp_new(0);
 	    }
+	    else if (NIL_P(location) ||
+		     NIL_P(path = rb_funcall(location, rb_intern("path"), 0))) {
+		str = rb_str_new_cstr("warning: ");
+	    }
 	    else {
-		VALUE path;
-		path = rb_funcall(uplevel, rb_intern("path"), 0);
 		str = rb_sprintf("%s:%ld: warning: ",
 		    rb_string_value_ptr(&path),
-		    NUM2LONG(rb_funcall(uplevel, rb_intern("lineno"), 0)));
+		    NUM2LONG(rb_funcall(location, rb_intern("lineno"), 0)));
 	    }
 	    RBASIC_SET_CLASS(str, rb_cWarningBuffer);
 	    rb_io_puts(argc, argv, str);
diff --git a/test/ruby/test_exception.rb b/test/ruby/test_exception.rb
index 574ffbc537..61521cbfff 100644
--- a/test/ruby/test_exception.rb
+++ b/test/ruby/test_exception.rb
@@ -1121,6 +1121,7 @@ $stderr = $stdout; raise "\x82\xa0"') do |outs, errs, status|
     warning = capture_warning_warn {obj.w(1)}
     assert_equal("#{__FILE__}:#{__LINE__-1}: warning: test warning\n", warning[0])
     assert_raise(ArgumentError) {warn("test warning", uplevel: -1)}
+    assert_in_out_err(["-e", "warn 'ok', uplevel: 1"], '', [], /warning:/)
   end
 
   def test_warning_warn_invalid_argument