diff --git a/hermes_cli/tools_config.py b/hermes_cli/tools_config.py
index 5290bd1b04..28b1a50cf0 100644
--- a/hermes_cli/tools_config.py
+++ b/hermes_cli/tools_config.py
@@ -849,7 +849,9 @@ def _get_platform_tools(
     # checklist or in a user-saved config.  Must run in BOTH branches —
     # otherwise saving via `hermes tools` (which flips has_explicit_config
     # to True) silently drops them.
-    platform_tool_universe = set(resolve_toolset(PLATFORMS[platform]["default_toolset"]))
+    _plat_info = PLATFORMS.get(platform)
+    _default_ts = _plat_info["default_toolset"] if _plat_info else f"hermes-{platform}"
+    platform_tool_universe = set(resolve_toolset(_default_ts))
     configurable_tool_universe = set()
     for ck in configurable_keys:
         configurable_tool_universe.update(resolve_toolset(ck))