diff --git a/pkgs/development/ocaml-modules/lwt/default.nix b/pkgs/development/ocaml-modules/lwt/default.nix
index 6d0a1f3d95d1..4f59e1ba747c 100644
--- a/pkgs/development/ocaml-modules/lwt/default.nix
+++ b/pkgs/development/ocaml-modules/lwt/default.nix
@@ -4,7 +4,7 @@
 
 buildDunePackage rec {
   pname = "lwt";
-  version = "5.9.0";
+  version = "5.9.1";
 
   minimalOCamlVersion = "4.08";
 
@@ -12,7 +12,7 @@ buildDunePackage rec {
     owner = "ocsigen";
     repo = "lwt";
     rev = version;
-    hash = "sha256-xYF+f489RI/nY0J48qW0jtq5GEnk68QnwxzBV2TLmLk=";
+    hash = "sha256-oPYLFugMTI3a+hmnwgUcoMgn5l88NP1Roq0agLhH/vI=";
   };
 
   nativeBuildInputs = [ cppo ];