diff --git a/pkgs/development/ocaml-modules/hmap/default.nix b/pkgs/development/ocaml-modules/hmap/default.nix
index 7021af3b8f3d..31b5b8d180c8 100644
--- a/pkgs/development/ocaml-modules/hmap/default.nix
+++ b/pkgs/development/ocaml-modules/hmap/default.nix
@@ -17,7 +17,7 @@ stdenv.mkDerivation rec {
   name = "ocaml${ocaml.version}-${pname}-${version}";
 
   src = fetchurl {
-    url = "http://erratique.ch/software/hmap/releases/${pname}-${version}.tbz";
+    url = "https://erratique.ch/software/hmap/releases/${pname}-${version}.tbz";
     sha256 = "10xyjy4ab87z7jnghy0wnla9wrmazgyhdwhr4hdmxxdn28dxn03a";
   };