diff --git a/src/mistral_common/protocol/instruct/validator.py b/src/mistral_common/protocol/instruct/validator.py
index ab3232d..c63339d 100644
--- a/src/mistral_common/protocol/instruct/validator.py
+++ b/src/mistral_common/protocol/instruct/validator.py
@@ -192,7 +192,7 @@ def _validate_message_order(self, messages: List[ChatMessage]) -> None:
                 elif previous_role == Roles.user:
                     expected_roles = {Roles.assistant, Roles.system, Roles.user}
                 elif previous_role == Roles.assistant:
-                    expected_roles = {Roles.user, Roles.tool}
+                    expected_roles = {Roles.assistant, Roles.user, Roles.tool}
                 elif previous_role == Roles.tool:
                     expected_roles = {Roles.assistant, Roles.tool}