diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index 4027809..89b4c4c 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -28,7 +28,11 @@
  *  http://csrc.nist.gov/publications/nistpubs/800-90/SP800-90revised_March2007.pdf
  */
 
+#if !defined(POLARSSL_CONFIG_FILE)
 #include "polarssl/config.h"
+#else
+#include POLARSSL_CONFIG_FILE
+#endif
 
 #if defined(POLARSSL_CTR_DRBG_C)