diff --git a/pkgs/applications/networking/instant-messengers/telegram/tdesktop/default.nix b/pkgs/applications/networking/instant-messengers/telegram/tdesktop/default.nix
index 1e8080fd9c9..b5994d03bc6 100644
--- a/pkgs/applications/networking/instant-messengers/telegram/tdesktop/default.nix
+++ b/pkgs/applications/networking/instant-messengers/telegram/tdesktop/default.nix
@@ -13,8 +13,8 @@ let
 in {
   stable = mkTelegram stableVersion;
   preview = mkTelegram (stableVersion // {
-    version = "1.4.4";
-    sha256Hash = "1m1j485r3vzpglzfn8l4cqskysvkx8l3pqaw3fgp66jfajbxynf0";
+    version = "1.4.7";
+    sha256Hash = "00kjirikywdbigm4zdnm50s3wxfn9bw1yx13xz4k4ppz6amq9nrp";
     stable = false;
   });
 }
diff --git a/pkgs/applications/networking/instant-messengers/telegram/tdesktop/generic.nix b/pkgs/applications/networking/instant-messengers/telegram/tdesktop/generic.nix
index e8f2c135fa8..63c3f9e0725 100644
--- a/pkgs/applications/networking/instant-messengers/telegram/tdesktop/generic.nix
+++ b/pkgs/applications/networking/instant-messengers/telegram/tdesktop/generic.nix
@@ -97,7 +97,9 @@ mkDerivation rec {
     sed -i Telegram/ThirdParty/libtgvoip/libtgvoip.gyp \
       -e "/-msse2/d"
 
-    gyp \
+    gyp ${lib.optionalString (!stable) ''
+        -Dapi_id=17349 \
+        -Dapi_hash=344583e45741c457fe1862106095a5eb ''}\
       -Dbuild_defines=${GYP_DEFINES} \
       -Gconfig=Release \
       --depth=Telegram/gyp \