Reserve -1 as an error code (used in programs)
diff --git a/include/polarssl/hmac_drbg.h b/include/polarssl/hmac_drbg.h
index 7f30c04..a9b4cff 100644
--- a/include/polarssl/hmac_drbg.h
+++ b/include/polarssl/hmac_drbg.h
@@ -30,12 +30,12 @@
 #include "md.h"
 
 /*
- * ! Same values as ctr_drbg.h !
+ * Error codes
  */
-#define POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED        -0x0001  /**< The entropy source failed. */
 #define POLARSSL_ERR_HMAC_DRBG_REQUEST_TOO_BIG              -0x0003  /**< Too many random requested in single call. */
 #define POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG                -0x0005  /**< Input too large (Entropy + additional). */
 #define POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR                -0x0007  /**< Read/write error in file. */
+#define POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED        -0x0009  /**< The entropy source failed. */
 
 #if !defined(POLARSSL_CONFIG_OPTIONS)
 #define POLARSSL_HMAC_DRBG_RESEED_INTERVAL   10000   /**< Interval before reseed is performed by default */