diff --git a/pkgs/development/ocaml-modules/chacha/default.nix b/pkgs/development/ocaml-modules/chacha/default.nix
index 21bae79ab5f8..ebd73b519f95 100644
--- a/pkgs/development/ocaml-modules/chacha/default.nix
+++ b/pkgs/development/ocaml-modules/chacha/default.nix
@@ -1,6 +1,7 @@
 { lib
 , buildDunePackage
-, fetchurl
+, fetchFromGitHub
+, fetchpatch
 , ocaml
 
 , alcotest
@@ -10,16 +11,22 @@
 
 buildDunePackage rec {
   pname = "chacha";
-  version = "1.0.0";
+  version = "1.1.0";
 
-  src = fetchurl {
-    url = "https://github.com/abeaumont/ocaml-chacha/releases/download/${version}/${pname}-${version}.tbz";
-    sha256 = "sha256-t8dOMQQDpje0QbuOhjSIa3xnXuXcxMVTLENa/rwdgA4=";
+  src = fetchFromGitHub {
+    owner = "abeaumont";
+    repo = "ocaml-chacha";
+    rev = version;
+    sha256 = "sha256-PmeiFloU0k3SqOK1VjaliiCEzDzrzyMSasgnO5fJS1k=";
   };
 
-  useDune2 = true;
+  # Ensure compatibility with cstruct ≥ 6.1.0
+  patches = [ (fetchpatch {
+    url = "https://github.com/abeaumont/ocaml-chacha/commit/fbe4a0a808226229728a68f278adf370251196fd.patch";
+    sha256 = "sha256-y7X9toFDrgdv3qmFmUs7K7QS+Gy45rRLulKy48m7uqc=";
+  })];
 
-  minimumOCamlVersion = "4.02";
+  minimalOCamlVersion = "4.02";
 
   propagatedBuildInputs = [ cstruct mirage-crypto ];