diff --git a/src/validate_pyproject/plugins/setuptools.schema.json b/src/validate_pyproject/plugins/setuptools.schema.json
index 11059e4..cafa6c8 100644
--- a/src/validate_pyproject/plugins/setuptools.schema.json
+++ b/src/validate_pyproject/plugins/setuptools.schema.json
@@ -199,7 +199,14 @@
         },
         "classifiers": {"$ref": "#/definitions/file-directive"},
         "description": {"$ref": "#/definitions/file-directive"},
+        "dependencies": {"$ref": "#/definitions/file-directive"},
         "entry-points": {"$ref": "#/definitions/file-directive"},
+        "optional-dependencies": {
+          "type": "object",
+          "propertyNames": {"format": "pep508-identifier"},
+          "additionalProperties": false,
+          "patternProperties": {".+": {"$ref": "#/definitions/file-directive"}}
+        },
         "readme": {
           "anyOf": [
             {"$ref": "#/definitions/file-directive"},
diff --git a/tests/invalid-examples/pretend-setuptools/dependencies/invalid-extra-name.errors.txt b/tests/invalid-examples/pretend-setuptools/dependencies/invalid-extra-name.errors.txt
new file mode 100644
index 0000000..922d9dd
--- /dev/null
+++ b/tests/invalid-examples/pretend-setuptools/dependencies/invalid-extra-name.errors.txt
@@ -0,0 +1,3 @@
+`tool.setuptools.dynamic.optional-dependencies` keys must be named by:
+
+    {format: 'pep508-identifier'}
diff --git a/tests/invalid-examples/pretend-setuptools/dependencies/invalid-extra-name.toml b/tests/invalid-examples/pretend-setuptools/dependencies/invalid-extra-name.toml
new file mode 100644
index 0000000..985baf6
--- /dev/null
+++ b/tests/invalid-examples/pretend-setuptools/dependencies/invalid-extra-name.toml
@@ -0,0 +1,7 @@
+[project]
+name = "myproj"
+version = "42"
+dynamic = ["optional-dependencies"]
+
+[tool.setuptools.dynamic.optional-dependencies."non pep508 compliant"]
+file = "extra.txt"