diff --git a/src/core/CCRandom.ml b/src/core/CCRandom.ml
index b4d75504..12d970e1 100644
--- a/src/core/CCRandom.ml
+++ b/src/core/CCRandom.ml
@@ -70,8 +70,7 @@ let float f st = Random.State.float st f
 
 let small_float = float 100.0
 
-let float_range i j st = i +. Random.State.float st (j-.i+.1.)
-
+let float_range i j st = i +. Random.State.float st (j-.i)
 
 let replicate n g st =
   let rec aux acc n =
diff --git a/src/core/CCRandom.mli b/src/core/CCRandom.mli
index 506fca86..05b05c8c 100644
--- a/src/core/CCRandom.mli
+++ b/src/core/CCRandom.mli
@@ -97,10 +97,9 @@ val float : float -> float t
     @since 0.6.1 *)
 
 val float_range : float -> float -> float t
-(** Inclusive range
+(** Inclusive range. [float_range a b] assumes [a < b].
     @since 0.6.1 *)
 
-
 val split : int -> (int * int) option t
 (** Split a positive value [n] into [n1,n2] where [n = n1 + n2].
     @return [None] if the value is too small *)