diff --git a/pylsp_ruff/plugin.py b/pylsp_ruff/plugin.py
index 2342b99..b9d41d3 100644
--- a/pylsp_ruff/plugin.py
+++ b/pylsp_ruff/plugin.py
@@ -492,7 +492,7 @@ def build_arguments(
     # Suppress update announcements
     args.append("--quiet")
     # Use the json formatting for easier evaluation
-    args.append("--format=json")
+    args.append("--output-format=json")
     if fix:
         args.append("--fix")
     else:
diff --git a/tests/test_ruff_lint.py b/tests/test_ruff_lint.py
index 9f6bac0..abcbada 100644
--- a/tests/test_ruff_lint.py
+++ b/tests/test_ruff_lint.py
@@ -177,7 +177,7 @@ def f():
     assert call_args == [
         "ruff",
         "--quiet",
-        "--format=json",
+        "--output-format=json",
         "--no-fix",
         "--force-exclude",
         f"--stdin-filename={os.path.join(workspace.root_path, '__init__.py')}",