diff --git a/silverback/cluster/client.py b/silverback/cluster/client.py
index ff4cfc5b..365305c5 100644
--- a/silverback/cluster/client.py
+++ b/silverback/cluster/client.py
@@ -480,8 +480,8 @@ def workspaces(self) -> dict[str, Workspace]:
 
     def create_workspace(
         self,
-        workspace_slug: str = "",
-        workspace_name: str = "",
+        workspace_slug: str | None = None,
+        workspace_name: str | None = None,
     ) -> Workspace:
         response = self.post(
             "/workspaces",