diff --git a/CHANGELOG.md b/CHANGELOG.md
index d1297a1b950..7380a84942a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+- Restrict syntax for setting default ink! e2e test runtime-only emulator - [#2143](https://github.com/paritytech/ink/pull/2143)
+
 ## Version 5.0.0-rc.2
 
 ### Added
diff --git a/crates/e2e/macro/src/config.rs b/crates/e2e/macro/src/config.rs
index aaec35b4b4e..b5d561c3480 100644
--- a/crates/e2e/macro/src/config.rs
+++ b/crates/e2e/macro/src/config.rs
@@ -66,6 +66,7 @@ impl Node {
 #[derive(Clone, Eq, PartialEq, Debug, darling::FromMeta)]
 pub enum RuntimeOnly {
     #[darling(word)]
+    #[darling(skip)]
     Default,
     Runtime(syn::Path),
 }
@@ -134,6 +135,18 @@ mod tests {
         assert_eq!(config.backend(), Backend::RuntimeOnly(RuntimeOnly::Default));
     }
 
+    #[test]
+    #[should_panic(expected = "ErrorUnknownField")]
+    fn config_works_backend_runtime_only_default_not_allowed() {
+        let input = quote! {
+            backend(runtime_only(default)),
+        };
+        let config =
+            E2EConfig::from_list(&NestedMeta::parse_meta_list(input).unwrap()).unwrap();
+
+        assert_eq!(config.backend(), Backend::RuntimeOnly(RuntimeOnly::Default));
+    }
+
     #[test]
     fn config_works_runtime_only_with_custom_backend() {
         let input = quote! {