diff --git a/cores/common/arduino/libraries/common/MD5/MD5.h b/cores/common/arduino/libraries/common/MD5/MD5.h
index 2971867..9530fec 100644
--- a/cores/common/arduino/libraries/common/MD5/MD5.h
+++ b/cores/common/arduino/libraries/common/MD5/MD5.h
@@ -4,6 +4,7 @@
 
 #include <Arduino.h>
 
+#if 0 // maybe simply using void* is easier? this is not C++ so it will link anyway
 // available built-in implementations
 #if LT_ARD_MD5_POLARSSL
 #include "MD5PolarSSLImpl.h"
@@ -14,6 +15,7 @@
 #if LT_ARD_MD5_HOSTAPD
 #include "MD5HostapdImpl.h"
 #endif
+#endif
 
 // common API
 #ifdef __cplusplus
diff --git a/cores/common/arduino/libraries/common/MD5/MD5MbedTLSImpl.cpp b/cores/common/arduino/libraries/common/MD5/MD5MbedTLSImpl.cpp
index 56744c5..8997282 100644
--- a/cores/common/arduino/libraries/common/MD5/MD5MbedTLSImpl.cpp
+++ b/cores/common/arduino/libraries/common/MD5/MD5MbedTLSImpl.cpp
@@ -2,20 +2,20 @@
 
 #if LT_ARD_MD5_MBEDTLS
 
-#include "MD5.h"
-
 extern "C" {
 
-void MD5Init(LT_MD5_CTX_T *context) {
+#include <mbedtls/md5.h>
+
+void MD5Init(mbedtls_md5_context *context) {
 	mbedtls_md5_init(context);
 	mbedtls_md5_starts(context);
 }
 
-void MD5Update(LT_MD5_CTX_T *context, const unsigned char *buf, unsigned len) {
+void MD5Update(mbedtls_md5_context *context, const unsigned char *buf, unsigned len) {
 	mbedtls_md5_update(context, buf, len);
 }
 
-void MD5Final(unsigned char digest[16], LT_MD5_CTX_T *context) {
+void MD5Final(unsigned char digest[16], mbedtls_md5_context *context) {
 	mbedtls_md5_finish(context, digest);
 }
 
diff --git a/cores/common/arduino/libraries/common/MD5/MD5PolarSSLImpl.cpp b/cores/common/arduino/libraries/common/MD5/MD5PolarSSLImpl.cpp
index d6642df..18f9d2c 100644
--- a/cores/common/arduino/libraries/common/MD5/MD5PolarSSLImpl.cpp
+++ b/cores/common/arduino/libraries/common/MD5/MD5PolarSSLImpl.cpp
@@ -2,20 +2,20 @@
 
 #if LT_ARD_MD5_POLARSSL
 
-#include "MD5.h"
-
 extern "C" {
 
-void MD5Init(LT_MD5_CTX_T *context) {
+#include <polarssl/md5.h>
+
+void MD5Init(md5_context *context) {
 	md5_init(context);
 	md5_starts(context);
 }
 
-void MD5Update(LT_MD5_CTX_T *context, const unsigned char *buf, unsigned len) {
+void MD5Update(md5_context *context, const unsigned char *buf, unsigned len) {
 	md5_update(context, buf, len);
 }
 
-void MD5Final(unsigned char digest[16], LT_MD5_CTX_T *context) {
+void MD5Final(unsigned char digest[16], md5_context *context) {
 	md5_finish(context, digest);
 }