diff --git a/library/oid.c b/library/oid.c
index 2a61193..2b52935 100644
--- a/library/oid.c
+++ b/library/oid.c
@@ -25,7 +25,11 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+#if !defined(POLARSSL_CONFIG_FILE)
 #include "polarssl/config.h"
+#else
+#include POLARSSL_CONFIG_FILE
+#endif
 
 #if defined(POLARSSL_OID_C)