diff --git a/include/mbedtls/platform.h b/include/mbedtls/platform.h
index ed10775..8e8a27e 100644
--- a/include/mbedtls/platform.h
+++ b/include/mbedtls/platform.h
@@ -50,6 +50,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>
+#include <stdarg.h>
 #if !defined(MBEDTLS_PLATFORM_STD_SNPRINTF)
 #if defined(_WIN32)
 #define MBEDTLS_PLATFORM_STD_SNPRINTF   mbedtls_platform_win32_snprintf /**< The default \c snprintf function to use.  */