diff --git a/include/polarssl/ctr_drbg.h b/include/polarssl/ctr_drbg.h
index 83861a9..5a26cde 100644
--- a/include/polarssl/ctr_drbg.h
+++ b/include/polarssl/ctr_drbg.h
@@ -3,7 +3,7 @@
  *
  * \brief CTR_DRBG based on AES-256 (NIST SP 800-90)
  *
- *  Copyright (C) 2006-2010, Brainspark B.V.
+ *  Copyright (C) 2006-2013, Brainspark B.V.
  *
  *  This file is part of PolarSSL (http://www.polarssl.org)
  *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
@@ -41,11 +41,14 @@
 #define CTR_DRBG_KEYBITS            ( CTR_DRBG_KEYSIZE * 8 )
 #define CTR_DRBG_SEEDLEN            ( CTR_DRBG_KEYSIZE + CTR_DRBG_BLOCKSIZE )
                                             /**< The seed length (counter + AES key)            */
-#define CTR_DRBG_ENTROPY_LEN        48      /**< Amount of entropy used per seed by default     */
+
+#if !defined(POLARSSL_CONFIG_OPTIONS)
+#define CTR_DRBG_ENTROPY_LEN        48      /**< Amount of entropy used per seed by default */
 #define CTR_DRBG_RESEED_INTERVAL    10000   /**< Interval before reseed is performed by default */
-#define CTR_DRBG_MAX_INPUT          256     /**< Maximum number of additional input bytes       */
-#define CTR_DRBG_MAX_REQUEST        1024    /**< Maximum number of requested bytes per call     */
-#define CTR_DRBG_MAX_SEED_INPUT     384     /**< Maximum size of (re)seed buffer                */
+#define CTR_DRBG_MAX_INPUT          256     /**< Maximum number of additional input bytes */
+#define CTR_DRBG_MAX_REQUEST        1024    /**< Maximum number of requested bytes per call */
+#define CTR_DRBG_MAX_SEED_INPUT     384     /**< Maximum size of (re)seed buffer */
+#endif /* !POLARSSL_CONFIG_OPTIONS */
 
 #define CTR_DRBG_PR_OFF             0       /**< No prediction resistance       */
 #define CTR_DRBG_PR_ON              1       /**< Prediction resistance enabled  */