diff --git a/dune-project b/dune-project
index 6c6d1452..9cb43285 100644
--- a/dune-project
+++ b/dune-project
@@ -32,7 +32,6 @@
   (ocaml (>= "5.1"))
   (odoc (and :with-doc (>= "2.2.2")))
   (ptime (>= "1.1.0"))
-  (randomconv (= "0.2.0"))
   (rio (>= "0.0.1"))
   (telemetry (>= "0.0.1"))
   (uri (>= "4.4.0"))
diff --git a/riot.opam b/riot.opam
index e9578891..72348321 100644
--- a/riot.opam
+++ b/riot.opam
@@ -21,7 +21,6 @@ depends: [
   "ocaml" {>= "5.1"}
   "odoc" {with-doc & >= "2.2.2"}
   "ptime" {>= "1.1.0"}
-  "randomconv" {= "0.2.0"}
   "rio" {>= "0.0.1"}
   "telemetry" {>= "0.0.1"}
   "uri" {>= "4.4.0"}
diff --git a/riot/lib/crypto.ml b/riot/lib/crypto.ml
index a1a5253a..2920108a 100644
--- a/riot/lib/crypto.ml
+++ b/riot/lib/crypto.ml
@@ -1,16 +1,58 @@
 let () = Mirage_crypto_rng_unix.initialize (module Mirage_crypto_rng.Fortuna)
 
+(* Some of the code from below is based on the randomconv repository.
+   Source: https://github.com/hannesm/randomconv/
+   The original code is licensed under the following license:
+
+   Copyright (c) 2016 Hannes Mehnert hannes@mehnert.org
+
+   Permission to use, copy, modify, and distribute this software for any
+   purpose with or without fee is hereby granted, provided that the above
+   copyright notice and this permission notice appear in all copies.
+   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+   MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+   ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*)
+
 module Random = struct
   let string n = Mirage_crypto_rng.generate n
-  let int8 () = Randomconv.int8 string
-  let int16 () = Randomconv.int16 string
-  let int32 () = Randomconv.int32 string
-  let int64 () = Randomconv.int64 string
+  let int8 () = Bytes.get_uint8 (Bytes.unsafe_of_string (string 1)) 0
+  let int16 () = Bytes.get_uint16_le (Bytes.unsafe_of_string (string 2)) 0
+  let int32 () = Bytes.get_int32_le (Bytes.unsafe_of_string (string 4)) 0
+  let int64 () = Bytes.get_int64_le (Bytes.unsafe_of_string (string 8)) 0
+
+  let bitmask n =
+    let rec go c = function 0 -> c | n -> go (c lsl 1) (n lsr 1) in
+    go 1 n - 1
+
+  let rec int ?(max = max_int) () =
+    if max <= 0 then invalid_arg "bound smaller or equal 0 not supported";
+    if max = 1 then 0
+    else
+      let r =
+        if max <= 256 then int8 ()
+        else if max <= 65536 then int16 ()
+        else
+          match Sys.word_size with
+          | 32 -> Int32.to_int (int32 ())
+          | 64 -> Int64.to_int (int64 ())
+          | _ -> invalid_arg "unknown word size"
+      in
+      let r = r land bitmask (pred max) in
+      if r < max then r else int ~max ()
+
+  let float ?(max = 1.) () =
+    if max <= 0. then invalid_arg "bound smaller or equal 0 not supported";
+    let scale = float_of_int max_int and r1 = int () and r2 = int () in
+    max *. (((float_of_int r1 /. scale) +. float_of_int r2) /. scale)
+
   let char () = Char.chr (int8 ())
-  let int ?max () = Randomconv.int ?bound:max string
-  let float ?max () = Randomconv.float ?bound:max string
   let bytes n = string n |> Bytes.unsafe_of_string
   let bytestring n = string n |> Bytestring.of_string
-  let alphanum () = Char.chr (48 + Randomconv.int ~bound:74 string)
+  let alphanum () = Char.chr (48 + int ~max:74 ())
   let seq n gen = List.init n (fun _ -> gen ()) |> List.to_seq |> String.of_seq
 end
diff --git a/riot/lib/dune b/riot/lib/dune
index 181f9d86..e2143b76 100644
--- a/riot/lib/dune
+++ b/riot/lib/dune
@@ -7,7 +7,6 @@
   riot_runtime
   bytestring
   telemetry
-  randomconv
   mirage-crypto
   mirage-crypto-rng
   mirage-crypto-rng.unix))