diff --git a/include/mbedtls/platform_time.h b/include/mbedtls/platform_time.h
index 5c9f076..246120e 100644
--- a/include/mbedtls/platform_time.h
+++ b/include/mbedtls/platform_time.h
@@ -42,7 +42,8 @@
 #if defined(MBEDTLS_PLATFORM_MS_TIME_TYPE_MACRO)
 typedef MBEDTLS_PLATFORM_MS_TIME_TYPE_MACRO mbedtls_ms_time_t;
 #else
-typedef signed long long mbedtls_ms_time_t;
+#include <stdint.h>
+typedef int64_t mbedtls_ms_time_t;
 #endif /* MBEDTLS_PLATFORM_MS_TIME_TYPE_MACRO */
 
 /**