diff --git a/news/586.bugfix b/news/586.bugfix
new file mode 100644
index 000000000..ffdaf308b
--- /dev/null
+++ b/news/586.bugfix
@@ -0,0 +1,2 @@
+Assignment of a dict to an existing node in a parent in struct mode no longer raises ValidationError
+
diff --git a/omegaconf/omegaconf.py b/omegaconf/omegaconf.py
index 66d8b77ca..f6dc0aeb3 100644
--- a/omegaconf/omegaconf.py
+++ b/omegaconf/omegaconf.py
@@ -898,6 +898,10 @@ def _node_wrap(
     ref_type: Any = Any,
 ) -> Node:
     node: Node
+    allow_objects = parent is not None and parent._get_flag("allow_objects") is True
+    flags = {"allow_objects": allow_objects} if allow_objects is not None else {}
+    dummy = OmegaConf.create(flags=flags)
+
     is_dict = is_primitive_dict(value) or is_dict_annotation(type_)
     is_list = (
         type(value) in (list, tuple)
@@ -909,7 +913,7 @@ def _node_wrap(
         node = DictConfig(
             content=value,
             key=key,
-            parent=parent,
+            parent=dummy,
             ref_type=type_,
             is_optional=is_optional,
             key_type=key_type,
@@ -920,7 +924,7 @@ def _node_wrap(
         node = ListConfig(
             content=value,
             key=key,
-            parent=parent,
+            parent=dummy,
             is_optional=is_optional,
             element_type=element_type,
             ref_type=ref_type,
@@ -932,33 +936,34 @@ def _node_wrap(
             is_optional=is_optional,
             content=value,
             key=key,
-            parent=parent,
+            parent=dummy,
             key_type=key_type,
             element_type=element_type,
         )
     elif type_ == Any or type_ is None:
-        node = AnyNode(value=value, key=key, parent=parent, is_optional=is_optional)
+        node = AnyNode(value=value, key=key, parent=dummy, is_optional=is_optional)
     elif issubclass(type_, Enum):
         node = EnumNode(
             enum_type=type_,
             value=value,
             key=key,
-            parent=parent,
+            parent=dummy,
             is_optional=is_optional,
         )
     elif type_ == int:
-        node = IntegerNode(value=value, key=key, parent=parent, is_optional=is_optional)
+        node = IntegerNode(value=value, key=key, parent=dummy, is_optional=is_optional)
     elif type_ == float:
-        node = FloatNode(value=value, key=key, parent=parent, is_optional=is_optional)
+        node = FloatNode(value=value, key=key, parent=dummy, is_optional=is_optional)
     elif type_ == bool:
-        node = BooleanNode(value=value, key=key, parent=parent, is_optional=is_optional)
+        node = BooleanNode(value=value, key=key, parent=dummy, is_optional=is_optional)
     elif type_ == str:
-        node = StringNode(value=value, key=key, parent=parent, is_optional=is_optional)
+        node = StringNode(value=value, key=key, parent=dummy, is_optional=is_optional)
     else:
-        if parent is not None and parent._get_flag("allow_objects") is True:
-            node = AnyNode(value=value, key=key, parent=parent, is_optional=is_optional)
+        if allow_objects:
+            node = AnyNode(value=value, key=key, parent=dummy, is_optional=is_optional)
         else:
             raise ValidationError(f"Unexpected object type : {type_str(type_)}")
+    node._set_parent(parent)
     return node
 
 
diff --git a/tests/test_struct.py b/tests/test_struct.py
index d15e23406..6bcc9f0e8 100644
--- a/tests/test_struct.py
+++ b/tests/test_struct.py
@@ -62,3 +62,10 @@ def test_struct_contain_missing() -> None:
 @mark.parametrize("cfg", [{}, OmegaConf.create({}, flags={"struct": True})])
 def test_struct_dict_get(cfg: Any) -> None:
     assert cfg.get("z") is None
+
+
+def test_struct_dict_assign() -> None:
+    cfg = OmegaConf.create({"a": {}})
+    OmegaConf.set_struct(cfg, True)
+    cfg.a = {"b": 10}
+    assert cfg.a == {"b": 10}