diff --git a/pkgs/development/compilers/unison/default.nix b/pkgs/development/compilers/unison/default.nix
index 3bdf234f9159..d4e536484c46 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 = "M1c";
+  milestone_id = "M1d";
   version = "1.0.${milestone_id}-alpha";
 
   src = if (stdenv.isDarwin) then
     fetchurl {
       url = "https://github.com/unisonweb/unison/releases/download/release/${milestone_id}/unison-osx.tar.gz";
-      sha256 = "03q02r7qc7ybqz16kmpk2d8l9vx28kaj9x59mlxzi8a4mr0j3vzb";
+      sha256 = "0cgkqwniw2fclsxgx6b1kgjmylqnn67kjs61iygzbpip8nvcm7pv";
     }
   else
     fetchurl {
       url = "https://github.com/unisonweb/unison/releases/download/release/${milestone_id}/unison-linux64.tar.gz";
-      sha256 = "1iwynqnp1i39pyq9wc01x7y22y1qa0rrjlx40jjdgnj23y1r6jk4";
+      sha256 = "0rpz40d23daad16r2s4appiay3brbk0awp38yamavlr6dh23c9ws";
     };
 
   # The tarball is just the prebuilt binary, in the archive root.