diff --git a/pkgs/development/compilers/unison/default.nix b/pkgs/development/compilers/unison/default.nix
index c17f85b4936a..c7266614e494 100644
--- a/pkgs/development/compilers/unison/default.nix
+++ b/pkgs/development/compilers/unison/default.nix
@@ -4,18 +4,18 @@
 
 stdenv.mkDerivation rec {
   pname = "unison-code-manager";
-  milestone_id = "M1l";
+  milestone_id = "M1m";
   version = "1.0.${milestone_id}-alpha";
 
   src = if (stdenv.isDarwin) then
     fetchurl {
       url = "https://github.com/unisonweb/unison/releases/download/release/${milestone_id}/unison-osx.tar.gz";
-      sha256 = "0qbxakrp3p3k3k8a1m2g24ivs3c8j5rj7ij84i7k548505rva9qr";
+      sha256 = "06pxvp753j8pr0pn02l7cswmmas5pk1vlkw83yd04h3f2rx1s61v";
     }
   else
     fetchurl {
       url = "https://github.com/unisonweb/unison/releases/download/release/${milestone_id}/unison-linux64.tar.gz";
-      sha256 = "152yzv7j4nyp228ngzbhki9fid1xdqrjvl1rwxc05wq30jwwqx0x";
+      sha256 = "1qspvfq805d34kz031pf9sqw8kzz7h637kc8lnbjlgvwixxkxc7c";
     };
 
   # The tarball is just the prebuilt binary, in the archive root.