diff --git a/examples/device/cdc_dual_ports/src/tusb_config.h b/examples/device/cdc_dual_ports/src/tusb_config.h
index 7db520dd1..c7e87bf67 100644
--- a/examples/device/cdc_dual_ports/src/tusb_config.h
+++ b/examples/device/cdc_dual_ports/src/tusb_config.h
@@ -64,8 +64,9 @@
   #error "Incorrect RHPort configuration"
 #endif
 
-// This example doesn't use an RTOS
+#ifndef CFG_TUSB_OS
 #define CFG_TUSB_OS                 OPT_OS_NONE
+#endif
 
 // CFG_TUSB_DEBUG is defined by compiler in DEBUG build
 // #define CFG_TUSB_DEBUG           0