diff --git a/library/md5.c b/library/md5.c
index c596e43..6ceab8a 100644
--- a/library/md5.c
+++ b/library/md5.c
@@ -28,7 +28,11 @@
  *  http://www.ietf.org/rfc/rfc1321.txt
  */
 
+#if !defined(POLARSSL_CONFIG_FILE)
 #include "polarssl/config.h"
+#else
+#include POLARSSL_CONFIG_FILE
+#endif
 
 #if defined(POLARSSL_MD5_C)