diff --git a/pyproject.toml b/pyproject.toml
index 92c6f5b8..ca10422c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -34,7 +34,7 @@ Homepage = "https://github.com/testing-cabal/testtools"
 [project.optional-dependencies]
 test = ["testscenarios", "testresources"]
 twisted = ["Twisted", "fixtures"]
-dev = ["ruff==0.12.11"]
+dev = ["ruff==0.13.0"]
 
 [tool.hatch.version]
 source = "vcs"
diff --git a/testtools/tests/test_assert_that.py b/testtools/tests/test_assert_that.py
index 84fae077..7f0ab8b3 100644
--- a/testtools/tests/test_assert_that.py
+++ b/testtools/tests/test_assert_that.py
@@ -115,7 +115,7 @@ def get_error_string(self, e):
                     break
             error = "".join(lines[i:])
         # We aren't interested in how the exception type is formatted.
-        exc_class, error = error.split(": ", 1)
+        _exc_class, error = error.split(": ", 1)
         return error
 
     def test_assertThat_verbose_unicode(self):
diff --git a/testtools/tests/test_content.py b/testtools/tests/test_content.py
index d30bf5eb..620c90f2 100644
--- a/testtools/tests/test_content.py
+++ b/testtools/tests/test_content.py
@@ -246,7 +246,7 @@ def test_postfix_content(self):
         self.assertEqual(expected, actual)
 
     def test___init___sets_content_type(self):
-        stack_lines, expected = self._get_stack_line_and_expected_output()
+        stack_lines, _expected = self._get_stack_line_and_expected_output()
         content = StackLinesContent(stack_lines)
         expected_content_type = ContentType(
             "text", "x-traceback", {"language": "python", "charset": "utf8"}
diff --git a/testtools/tests/test_testcase.py b/testtools/tests/test_testcase.py
index b4d41e59..946a12d3 100644
--- a/testtools/tests/test_testcase.py
+++ b/testtools/tests/test_testcase.py
@@ -802,7 +802,7 @@ def get_error_string(self, e):
                     break
             error = "".join(lines[i:])
         # We aren't interested in how the exception type is formatted.
-        exc_class, error = error.split(": ", 1)
+        _exc_class, error = error.split(": ", 1)
         return error
 
     def test_assertThat_verbose_unicode(self):
diff --git a/testtools/tests/test_testresult.py b/testtools/tests/test_testresult.py
index d464e674..366d7ef6 100644
--- a/testtools/tests/test_testresult.py
+++ b/testtools/tests/test_testresult.py
@@ -2574,7 +2574,7 @@ def check_outcome_details_to_exec_info(self, outcome, expected=None):
         # of the text types in the details dict.
         if not expected:
             expected = outcome
-        details, err_str = self.get_details_and_string()
+        details, _err_str = self.get_details_and_string()
         getattr(self.converter, outcome)(self, details=details)
         err = self.converter._details_to_exc_info(details)
         self.assertEqual([(expected, self, err)], self.result._events)
@@ -3079,7 +3079,7 @@ def test_syntax_error_malformed(self):
 
     def test_syntax_error_line_iso_8859_1(self):
         """Syntax error on a latin-1 line shows the line decoded"""
-        text, raw = self._get_sample_text("iso-8859-1")
+        text, _raw = self._get_sample_text("iso-8859-1")
         textoutput = self._setup_external_case("import bad")
         self._write_module(
             "bad", "iso-8859-1", f"# coding: iso-8859-1\n! = 0 # {text}\n"
@@ -3095,7 +3095,7 @@ def test_syntax_error_line_iso_8859_1(self):
 
     def test_syntax_error_line_iso_8859_5(self):
         """Syntax error on a iso-8859-5 line shows the line decoded"""
-        text, raw = self._get_sample_text("iso-8859-5")
+        text, _raw = self._get_sample_text("iso-8859-5")
         textoutput = self._setup_external_case("import bad")
         self._write_module(
             "bad", "iso-8859-5", f"# coding: iso-8859-5\n% = 0 # {text}\n"
@@ -3118,7 +3118,7 @@ def test_syntax_error_line_iso_8859_5(self):
 
     def test_syntax_error_line_euc_jp(self):
         """Syntax error on a euc_jp line shows the line decoded"""
-        text, raw = self._get_sample_text("euc_jp")
+        text, _raw = self._get_sample_text("euc_jp")
         textoutput = self._setup_external_case("import bad")
         self._write_module("bad", "euc_jp", f"# coding: euc_jp\n$ = 0 # {text}\n")
         textoutput = self._run_external_case()
@@ -3139,7 +3139,7 @@ def test_syntax_error_line_euc_jp(self):
 
     def test_syntax_error_line_utf_8(self):
         """Syntax error on a utf-8 line shows the line decoded"""
-        text, raw = self._get_sample_text("utf-8")
+        text, _raw = self._get_sample_text("utf-8")
         textoutput = self._setup_external_case("import bad")
         self._write_module("bad", "utf-8", f"\ufeff^ = 0 # {text}\n")
         textoutput = self._run_external_case()
diff --git a/testtools/tests/twistedsupport/test_runtest.py b/testtools/tests/twistedsupport/test_runtest.py
index 222b057a..9a4e4a4f 100644
--- a/testtools/tests/twistedsupport/test_runtest.py
+++ b/testtools/tests/twistedsupport/test_runtest.py
@@ -817,7 +817,7 @@ def test_something(self):
 
     def test_restore_observers(self):
         # We restore the original observers.
-        publisher, observers = _get_global_publisher_and_observers()
+        _publisher, observers = _get_global_publisher_and_observers()
 
         class LogSomething(TestCase):
             def test_something(self):
@@ -831,7 +831,7 @@ def test_something(self):
 
     def test_restore_observers_after_timeout(self):
         # We restore the original observers even if the test times out.
-        publisher, observers = _get_global_publisher_and_observers()
+        _publisher, observers = _get_global_publisher_and_observers()
 
         class LogSomething(TestCase):
             def test_something(self):