diff --git a/litellm/proxy/_experimental/mcp_server/mcp_server_manager.py b/litellm/proxy/_experimental/mcp_server/mcp_server_manager.py
index 7c211d48abe..fbb0603100e 100644
--- a/litellm/proxy/_experimental/mcp_server/mcp_server_manager.py
+++ b/litellm/proxy/_experimental/mcp_server/mcp_server_manager.py
@@ -891,15 +891,15 @@ class MCPServerManager:
 
         # Handle stdio transport
         if transport == MCPTransport.stdio:
-            # For stdio, we need to get the stdio config from the server
-            resolved_env = stdio_env if stdio_env is not None else server.env or {}
+            resolved_env = stdio_env if stdio_env is not None else dict(server.env or {})
 
             # Ensure npm-based STDIO MCP servers have a writable cache dir.
             # In containers the default (~/.npm or /app/.npm) may not exist
             # or be read-only, causing npx to fail with ENOENT.
             if "NPM_CONFIG_CACHE" not in resolved_env:
-                resolved_env["NPM_CONFIG_CACHE"] = MCP_NPM_CACHE_DIR
+                from litellm.constants import MCP_NPM_CACHE_DIR
 
+                resolved_env["NPM_CONFIG_CACHE"] = MCP_NPM_CACHE_DIR
             stdio_config: Optional[MCPStdioConfig] = None
             if server.command and server.args is not None:
                 stdio_config = MCPStdioConfig(