diff --git a/include/polarssl/hmac_drbg.h b/include/polarssl/hmac_drbg.h
index 1f830d843..36d120049 100644
--- a/include/polarssl/hmac_drbg.h
+++ b/include/polarssl/hmac_drbg.h
@@ -37,13 +37,13 @@
 #define POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG                -0x0038  /**< Input too large (Entropy + additional). */
 #define POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR                -0x003A  /**< Read/write error in file. */
 
-#define HMAC_DRBG_RESEED_INTERVAL   10000   /**< Interval before reseed is performed by default */
-#define HMAC_DRBG_MAX_INPUT         256     /**< Maximum number of additional input bytes */
-#define HMAC_DRBG_MAX_REQUEST       1024    /**< Maximum number of requested bytes per call */
-#define HMAC_DRBG_MAX_SEED_INPUT    384     /**< Maximum size of (re)seed buffer */
+#define POLARSSL_HMAC_DRBG_RESEED_INTERVAL   10000   /**< Interval before reseed is performed by default */
+#define POLARSSL_HMAC_DRBG_MAX_INPUT         256     /**< Maximum number of additional input bytes */
+#define POLARSSL_HMAC_DRBG_MAX_REQUEST       1024    /**< Maximum number of requested bytes per call */
+#define POLARSSL_HMAC_DRBG_MAX_SEED_INPUT    384     /**< Maximum size of (re)seed buffer */
 
-#define HMAC_DRBG_PR_OFF        0       /**< No prediction resistance       */
-#define HMAC_DRBG_PR_ON         1       /**< Prediction resistance enabled  */
+#define POLARSSL_HMAC_DRBG_PR_OFF   0   /**< No prediction resistance       */
+#define POLARSSL_HMAC_DRBG_PR_ON    1   /**< Prediction resistance enabled  */
 
 #ifdef __cplusplus
 extern "C" {
@@ -125,7 +125,7 @@ int hmac_drbg_init_buf( hmac_drbg_context *ctx,
  *       Only use this if you have ample supply of good entropy!
  *
  * \param ctx           HMAC_DRBG context
- * \param resistance    HMAC_DRBG_PR_ON or HMAC_DRBG_PR_OFF
+ * \param resistance    POLARSSL_HMAC_DRBG_PR_ON or POLARSSL_HMAC_DRBG_PR_OFF
  */
 void hmac_drbg_set_prediction_resistance( hmac_drbg_context *ctx,
                                           int resistance );
@@ -143,7 +143,7 @@ void hmac_drbg_set_entropy_len( hmac_drbg_context *ctx,
 
 /**
  * \brief               Set the reseed interval
- *                      (Default: HMAC_DRBG_RESEED_INTERVAL)
+ *                      (Default: POLARSSL_HMAC_DRBG_RESEED_INTERVAL)
  *
  * \param ctx           HMAC_DRBG context
  * \param interval      Reseed interval
diff --git a/library/hmac_drbg.c b/library/hmac_drbg.c
index 4195bf1f6..43ab8f2a0 100644
--- a/library/hmac_drbg.c
+++ b/library/hmac_drbg.c
@@ -90,17 +90,17 @@ int hmac_drbg_init_buf( hmac_drbg_context *ctx,
 int hmac_drbg_reseed( hmac_drbg_context *ctx,
                       const unsigned char *additional, size_t len )
 {
-    unsigned char seed[HMAC_DRBG_MAX_SEED_INPUT];
+    unsigned char seed[POLARSSL_HMAC_DRBG_MAX_SEED_INPUT];
     size_t seedlen;
 
     /* III. Check input length */
-    if( len > HMAC_DRBG_MAX_INPUT ||
-        ctx->entropy_len + len > HMAC_DRBG_MAX_SEED_INPUT )
+    if( len > POLARSSL_HMAC_DRBG_MAX_INPUT ||
+        ctx->entropy_len + len > POLARSSL_HMAC_DRBG_MAX_SEED_INPUT )
     {
         return( POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG );
     }
 
-    memset( seed, 0, HMAC_DRBG_MAX_SEED_INPUT );
+    memset( seed, 0, POLARSSL_HMAC_DRBG_MAX_SEED_INPUT );
 
     /* IV. Gather entropy_len bytes of entropy for the seed */
     if( ctx->f_entropy( ctx->p_entropy, seed, ctx->entropy_len ) != 0 )
@@ -150,7 +150,7 @@ int hmac_drbg_init( hmac_drbg_context *ctx,
     ctx->f_entropy = f_entropy;
     ctx->p_entropy = p_entropy;
 
-    ctx->reseed_interval = HMAC_DRBG_RESEED_INTERVAL;
+    ctx->reseed_interval = POLARSSL_HMAC_DRBG_RESEED_INTERVAL;
 
     /*
      * See SP800-57 5.6.1 (p. 65-66) for the security strength provided by
@@ -217,16 +217,16 @@ int hmac_drbg_random_with_add( void *p_rng,
     unsigned char *out = output;
 
     /* II. Check request length */
-    if( out_len > HMAC_DRBG_MAX_REQUEST )
+    if( out_len > POLARSSL_HMAC_DRBG_MAX_REQUEST )
         return( POLARSSL_ERR_HMAC_DRBG_REQUEST_TOO_BIG );
 
     /* III. Check input length */
-    if( add_len > HMAC_DRBG_MAX_INPUT )
+    if( add_len > POLARSSL_HMAC_DRBG_MAX_INPUT )
         return( POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG );
 
     /* 1. (aka VII and IX) Check reseed counter and PR */
-    if( ctx->f_entropy != NULL &&
-        ( ctx->prediction_resistance == HMAC_DRBG_PR_ON ||
+    if( ctx->f_entropy != NULL && /* For no-reseeding instances */
+        ( ctx->prediction_resistance == POLARSSL_HMAC_DRBG_PR_ON ||
           ctx->reseed_counter > ctx->reseed_interval ) )
     {
         if( ( ret = hmac_drbg_reseed( ctx, additional, add_len ) ) != 0 )