diff --git a/README.md b/README.md
index 75f7a9b7..550e453f 100644
--- a/README.md
+++ b/README.md
@@ -86,8 +86,8 @@ dora stop c95d118b-cded-4531-a0e4-cd85b7c3916c
 
 7. You can then add or modify operators or nodes. For adding nodes easily, you can use the `dora` CLI again:
 
-- Run `dora new --kind operator --lang Rust <name>` to create a new Rust operator named `<name>`.
-- Run `dora new --kind custom-node --lang Rust <name>` to create a new custom node named `<name>`.
+- Run `dora new --kind operator --lang rust <name>` to create a new Rust operator named `<name>`.
+- Run `dora new --kind custom-node --lang rust <name>` to create a new custom node named `<name>`.
 
 You need to add the created operators/nodes to your dataflow YAML file.
 
diff --git a/libraries/core/src/descriptor/mod.rs b/libraries/core/src/descriptor/mod.rs
index 8dfdc689..3af99dda 100644
--- a/libraries/core/src/descriptor/mod.rs
+++ b/libraries/core/src/descriptor/mod.rs
@@ -154,6 +154,7 @@ pub struct SingleOperatorDefinition {
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone)]
+#[serde(deny_unknown_fields)]
 pub struct OperatorConfig {
     pub name: Option<String>,
     pub description: Option<String>,
@@ -202,6 +203,7 @@ pub fn resolve_path(source: &str, working_dir: &Path) -> Result<PathBuf> {
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone)]
+#[serde(deny_unknown_fields)]
 pub struct PythonOperatorConfig {
     pub path: PathBuf,
     #[serde(default)]
@@ -211,6 +213,7 @@ pub struct PythonOperatorConfig {
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
 pub struct CustomNode {
     pub source: String,
     #[serde(default, skip_serializing_if = "Option::is_none")]