diff --git a/include/polarssl/oid.h b/include/polarssl/oid.h
index d825f4c..b1d33b6 100644
--- a/include/polarssl/oid.h
+++ b/include/polarssl/oid.h
@@ -28,7 +28,11 @@
 #define POLARSSL_OID_H
 
 #include <string.h>
+#if !defined(POLARSSL_CONFIG_FILE)
 #include "config.h"
+#else
+#include POLARSSL_CONFIG_FILE
+#endif
 #include "asn1.h"
 #include "pk.h"
 #if defined(POLARSSL_CIPHER_C)