diff --git a/pylsp_ruff/plugin.py b/pylsp_ruff/plugin.py
index 2c3f3d9..4a05017 100644
--- a/pylsp_ruff/plugin.py
+++ b/pylsp_ruff/plugin.py
@@ -224,7 +224,7 @@ def create_diagnostic(check: RuffCheck, settings: PluginSettings) -> Diagnostic:
     # Ruff intends to implement severity codes in the future,
     # see https://github.com/charliermarsh/ruff/issues/645.
     severity = DiagnosticSeverity.Warning
-    if check.code == "None" or check.code == "E999" or check.code[0] == "F":
+    if check.code == "None" or check.code == "invalid-syntax" or check.code[0] == "F":
         severity = DiagnosticSeverity.Error
 
     # Check if check.code starts contained in given severities
diff --git a/pyproject.toml b/pyproject.toml
index 85883b0..72697d4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -13,7 +13,7 @@ readme = "README.md"
 requires-python = ">=3.8"
 license = {text = "MIT"}
 dependencies = [
-  "ruff>=0.2.0",
+  "ruff>=0.8.0",
   "python-lsp-server",
 	"cattrs!=23.2.1",
   "lsprotocol>=2023.0.1",
diff --git a/tests/test_ruff_lint.py b/tests/test_ruff_lint.py
index fa915fc..52ef6a5 100644
--- a/tests/test_ruff_lint.py
+++ b/tests/test_ruff_lint.py
@@ -24,6 +24,10 @@ def using_const():
     return t
 """
 
+DOC_INVALID = r"""
+a = 
+"""
+
 
 @pytest.fixture()
 def workspace(tmp_path):
@@ -74,6 +78,24 @@ def test_ruff_lint(workspace):
         os.remove(name)
 
 
+def test_ruff_invalid(workspace):
+    name, doc = temp_document(DOC_INVALID, workspace)
+    try:
+        diags = ruff_lint.pylsp_lint(workspace, doc)
+        assert len(diags) == 1
+        diag = diags[0]
+
+        assert diag["source"] == "ruff"
+        assert diag["code"] == "invalid-syntax"
+        assert diag["message"] == "Expected an expression"
+        assert diag["range"]["start"] == {"line": 1, "character": 4}
+        assert diag["range"]["end"] == {"line": 2, "character": 0}
+        assert diag["severity"] == lsp.DiagnosticSeverity.Error
+        assert diag["tags"] == []
+    finally:
+        os.remove(name)
+
+
 def test_ruff_config_param(workspace):
     with patch("pylsp_ruff.plugin.Popen") as popen_mock:
         mock_instance = popen_mock.return_value
@@ -268,7 +290,7 @@ def f():
 
     diags = ruff_lint.pylsp_lint(workspace, doc)
     diag_codes = [diag["code"] for diag in diags]
-    assert "E999" not in diag_codes
+    assert "invalid-syntax" not in diag_codes
     assert "E402" in diag_codes
     assert "F401" in diag_codes
     assert "F841" in diag_codes