diff --git a/pkgs/servers/mautrix-telegram/default.nix b/pkgs/servers/mautrix-telegram/default.nix
index 74280f048ce..dce4ad4117d 100644
--- a/pkgs/servers/mautrix-telegram/default.nix
+++ b/pkgs/servers/mautrix-telegram/default.nix
@@ -13,19 +13,21 @@ let
 
 in buildPythonPackage rec {
   pname = "mautrix-telegram";
-  version = "0.9.0";
-  disabled = pythonOlder "3.7";
+  version = "unstable-2021-08-12";
+  disabled = python.pythonOlder "3.7";
 
   src = fetchFromGitHub {
     owner = "tulir";
     repo = pname;
-    rev = "v${version}";
-    sha256 = "1543ljjl3jg3ayid7ifi4bamqh4gq85pmlbs3m8i7phjbbm7g9dn";
+    rev = "ec64c83cb01791525a39f937f3b847368021dce8";
+    sha256 = "0rg4f4abdddhhf1xpz74y4468dv3mnm7k8nj161r1xszrk9f2n76";
   };
 
   patches = [ ./0001-Re-add-entrypoint.patch ./0002-Don-t-depend-on-pytest-runner.patch ];
   postPatch = ''
     sed -i -e '/alembic>/d' requirements.txt
+    substituteInPlace requirements.txt \
+      --replace "telethon>=1.22,<1.23" "telethon"
   '';
 
   propagatedBuildInputs = [