diff --git a/library/x509write_csr.c b/library/x509write_csr.c
index 3a49aee..6e7bed4 100644
--- a/library/x509write_csr.c
+++ b/library/x509write_csr.c
@@ -28,7 +28,11 @@
  * - attributes: PKCS#9 v2.0 aka RFC 2985
  */
 
+#if !defined(POLARSSL_CONFIG_FILE)
 #include "polarssl/config.h"
+#else
+#include POLARSSL_CONFIG_FILE
+#endif
 
 #if defined(POLARSSL_X509_CSR_WRITE_C)