diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0f6e3edd2..7b4fd04e8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 # 2.5.2
 
 * Observable objects can now have a type: `IObservableObject`, see [#484](https://github.com/mobxjs/mobx/pull/484) by @spiffytech
+* Restored 2.4 behavior of boxed observables inside observable objects, see [#558](https://github.com/mobxjs/mobx/issues/558)
 
 # 2.5.1
 
diff --git a/src/types/observableobject.ts b/src/types/observableobject.ts
index b526bdeb5..b52ca4a7e 100644
--- a/src/types/observableobject.ts
+++ b/src/types/observableobject.ts
@@ -89,11 +89,10 @@ export function defineObservableProperty(adm: ObservableObjectAdministration, pr
 	let name = `${adm.name}.${propName}`;
 	let isComputed = true;
 
-	if (newValue instanceof ObservableValue) {
-		observable = newValue;
-		newValue.name = name;
-		isComputed = false;
-	} else if (newValue instanceof ComputedValue) {
+	if (newValue instanceof ComputedValue) {
+		// desugger computed(getter, setter)
+		// TODO: deprecate this and remove in 3.0, to keep them boxed
+		// get / set is now the idiomatic syntax for non-boxed computed values
 		observable = newValue;
 		newValue.name = name;
 		if (!newValue.scope)
diff --git a/test/observables.js b/test/observables.js
index 65fad621e..bfe4d8b5b 100644
--- a/test/observables.js
+++ b/test/observables.js
@@ -1892,3 +1892,13 @@ test('helpful error for self referencing setter', function(t) {
 
 	t.end()
 })
+
+test('#558 boxed observables stay boxed observables', function(t) {
+	var a = observable({
+		x: observable(3)
+	})
+
+	t.equal(typeof a.x, "object")
+	t.equal(typeof a.x.get, "function")
+	t.end()
+})