diff --git a/pkgs/development/compilers/unison/default.nix b/pkgs/development/compilers/unison/default.nix
index b5031fa58973..0fd99ac0c375 100644
--- a/pkgs/development/compilers/unison/default.nix
+++ b/pkgs/development/compilers/unison/default.nix
@@ -6,18 +6,18 @@
 
 stdenv.mkDerivation rec {
   pname = "unison-code-manager";
-  milestone_id = "M4h";
+  milestone_id = "M4i";
   version = "1.0.${milestone_id}-alpha";
 
   src = if (stdenv.isDarwin) then
     fetchurl {
       url = "https://github.com/unisonweb/unison/releases/download/release/${milestone_id}/ucm-macos.tar.gz";
-      hash = "sha256-7yphap7qZBkbTKiwhyCTLgbBO/aA0eUWtva+XjpaZDI=";
+      hash = "sha256-1Qp1SB5rCsVimZzRo1NOX8HBoMEGlIycJPm3zGTUuOw=";
     }
   else
     fetchurl {
       url = "https://github.com/unisonweb/unison/releases/download/release/${milestone_id}/ucm-linux.tar.gz";
-      hash = "sha256-vrZpYFoQw1hxgZ7lAoejIqnjIOFFMahAI9SjFN/Cnms=";
+      hash = "sha256-Qx8vO/Vaz0VdCGXwIwRQIuMlp44hxCroQ7m7Y+m7aXk=";
     };
 
   # The tarball is just the prebuilt binary, in the archive root.