diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 236a1f8..79ddc23 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -1837,8 +1837,24 @@
 #endif
 }
 
-void mbedtls_ssl_update_checksum( mbedtls_ssl_context *,
-                                  const unsigned char *, size_t );
+MBEDTLS_ALWAYS_INLINE static inline void mbedtls_ssl_update_checksum(
+    mbedtls_ssl_context *ssl,
+    const unsigned char *buf, size_t len )
+{
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_1)
+     mbedtls_md5_update_ret( &ssl->handshake->fin_md5 , buf, len );
+    mbedtls_sha1_update_ret( &ssl->handshake->fin_sha1, buf, len );
+#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#if defined(MBEDTLS_SHA256_C)
+    mbedtls_sha256_update_ret( &ssl->handshake->fin_sha256, buf, len );
+#endif
+#if defined(MBEDTLS_SHA512_C)
+    mbedtls_sha512_update_ret( &ssl->handshake->fin_sha512, buf, len );
+#endif
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+}
 
 #define MBEDTLS_SSL_CHK(f) do { if( ( ret = f ) < 0 ) goto cleanup; } while( 0 )