diff --git a/pkgs/by-name/si/signal-desktop/package.nix b/pkgs/by-name/si/signal-desktop/package.nix
index bc85b6048099..9fd84b6a07e2 100644
--- a/pkgs/by-name/si/signal-desktop/package.nix
+++ b/pkgs/by-name/si/signal-desktop/package.nix
@@ -60,7 +60,10 @@ let
     owner = "signalapp";
     repo = "Signal-Desktop";
     tag = "v${version}";
-    hash = "sha256-hzeioXrO9kdFFTGhhY4klrCxRgS1eoGY7+7fTGsN4cY=";
+    hash = "sha256-r1RB6vtG2mdRJifaKNrmQvxJxXOqkpHoWivvPPpesow=";
+    postCheckout = ''
+      git -C "$out" show -s --format=%ct > "$out"/GIT_COMMIT_TIME
+    '';
   };
 
   sticker-creator = stdenv.mkDerivation (finalAttrs: {
@@ -127,6 +130,10 @@ stdenv.mkDerivation (finalAttrs: {
     # it at runtime.
     substituteInPlace app/updateDefaultSession.main.ts \
       --replace-fail "\''${process.versions.electron}" "`jq -r '.devDependencies.electron' < package.json`"
+
+    # https://github.com/signalapp/Signal-Desktop/issues/7667
+    substituteInPlace ts/util/version.std.ts \
+      --replace-fail 'isAdhoc(version)' 'true'
   '';
 
   pnpmDeps = fetchPnpmDeps {
@@ -148,9 +155,12 @@ stdenv.mkDerivation (finalAttrs: {
   env = {
     ELECTRON_SKIP_BINARY_DOWNLOAD = "1";
     SIGNAL_ENV = "production";
-    SOURCE_DATE_EPOCH = 1766066770;
   };
 
+  preConfigure = ''
+    export SOURCE_DATE_EPOCH=`cat GIT_COMMIT_TIME`
+  '';
+
   preBuild = ''
     if [ "`jq -r '.engines.node' < package.json | cut -d. -f1`" != "${lib.versions.major nodejs.version}" ]
     then
diff --git a/pkgs/by-name/si/signal-desktop/update.sh b/pkgs/by-name/si/signal-desktop/update.sh
index d4dca6e74ef8..a39078678c1d 100755
--- a/pkgs/by-name/si/signal-desktop/update.sh
+++ b/pkgs/by-name/si/signal-desktop/update.sh
@@ -13,8 +13,6 @@ releaseInfo="`curl_github \
   "https://api.github.com/repos/signalapp/Signal-Desktop/releases/latest"`"
 
 releaseTag="`jq -r ".tag_name" <<< $releaseInfo`"
-releaseDate="`jq -r ".created_at" <<< $releaseInfo`"
-releaseEpoch=`date -d $releaseDate +%s`
 
 packageJson="`curl_github "https://raw.githubusercontent.com/signalapp/Signal-Desktop/refs/tags/$releaseTag/package.json"`"
 
@@ -29,7 +27,6 @@ webrtcVersion="`grep --only-matching "^webrtc.version=.*$" <<< $ringrtcVersionPr
 
 sed -E -i "s/(nodejs_)../\1$nodeVersion/" $SCRIPT_DIR/package.nix
 sed -E -i "s/(electron_)../\1$electronVersion/" $SCRIPT_DIR/package.nix
-sed -E -i "s/(SOURCE_DATE_EPOCH = )[0-9]+/\1$releaseEpoch/" $SCRIPT_DIR/package.nix
 
 sed -E -i "s/(withAppleEmojis \? )false/\1true/" $SCRIPT_DIR/package.nix
 nix-update signal-desktop --subpackage sticker-creator --version="$latestVersion"