diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index d3c9a9f..18e6b56 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -454,6 +454,12 @@
 #error "MBEDTLS_PLATFORM_MS_TIME_TYPE_MACRO defined, but not all prerequisites"
 #endif
 
+#if defined(MBEDTLS_PLATFORM_MS_TIME_ALT)   && \
+    ( !defined(MBEDTLS_PLATFORM_C)          || \
+        !defined(MBEDTLS_HAVE_TIME) )
+#error "MBEDTLS_PLATFORM_MS_TIME_ALT defined, but not all prerequisites"
+#endif
+
 #if defined(MBEDTLS_PLATFORM_TIME_TYPE_MACRO) &&\
     ( !defined(MBEDTLS_PLATFORM_C) ||\
         !defined(MBEDTLS_HAVE_TIME) )
diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index 34fdfcc..cfde4b7 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -234,6 +234,7 @@
 //#define MBEDTLS_PLATFORM_VSNPRINTF_ALT
 //#define MBEDTLS_PLATFORM_NV_SEED_ALT
 //#define MBEDTLS_PLATFORM_SETUP_TEARDOWN_ALT
+//#define MBEDTLS_PLATFORM_MS_TIME_ALT
 
 /**
  * \def MBEDTLS_DEPRECATED_WARNING
diff --git a/include/mbedtls/platform_time.h b/include/mbedtls/platform_time.h
index e6f7e23..1161807 100644
--- a/include/mbedtls/platform_time.h
+++ b/include/mbedtls/platform_time.h
@@ -45,6 +45,16 @@
 typedef signed long long mbedtls_ms_time_t;
 #endif /* MBEDTLS_PLATFORM_MS_TIME_TYPE_MACRO */
 
+/**
+ * \brief Get time in milliseconds.
+ *
+ * \return Current time in milliseconds
+ *
+ * \note If MBEDTLS_PLATFORM_MS_TIME_ALT defined, users can provide their own
+ *       implementation.
+ */
+mbedtls_ms_time_t mbedtls_ms_time(void);
+
 /*
  * The function pointers for time
  */