diff --git a/mongoose.h b/mongoose.h
index 64a9250b..1067ed3b 100644
--- a/mongoose.h
+++ b/mongoose.h
@@ -548,7 +548,7 @@ typedef struct stat cs_stat_t;
 #define __cdecl
 #define _FILE_OFFSET_BITS 32
 
-#ifndef RTOS_SDK
+#if !defined(RTOS_SDK) && !defined(__cplusplus)
 #define fileno(x) -1
 #endif