diff --git a/src/rand.h b/src/rand.h
index 475830f..e062d18 100644
--- a/src/rand.h
+++ b/src/rand.h
@@ -29,12 +29,14 @@
 /**
  * The maximal integer that is given by
  * ntru_get_urnd_poly_big and ntru_get_rnd_poly_big
+ * this number must be positiv
  */
 #define BIG_RAND_MAX 100
 
 /**
  * The minimal integer that is given by
  * ntru_get_urnd_poly_big and ntru_get_rnd_poly_big
+ * this number must be negativ
  */
 #define BIG_RAND_MIN -100