diff --git a/library/pbkdf2.c b/library/pbkdf2.c
index 09e56df..6572274 100644
--- a/library/pbkdf2.c
+++ b/library/pbkdf2.c
@@ -34,7 +34,11 @@
  * http://tools.ietf.org/html/rfc6070 (Test vectors)
  */
 
+#if !defined(POLARSSL_CONFIG_FILE)
 #include "polarssl/config.h"
+#else
+#include POLARSSL_CONFIG_FILE
+#endif
 
 #if defined(POLARSSL_PBKDF2_C)