diff --git a/app/build.sh b/app/build.sh
index de092bde16..2e58b687e7 100755
--- a/app/build.sh
+++ b/app/build.sh
@@ -241,7 +241,8 @@ if [ "$UPDATE_CHANNEL" == "beta" ] || [ "$UPDATE_CHANNEL" == "dev" ] || [ "$UPDA
 	DEVTOOLS=1
 fi
 if [ -z "$UPDATE_CHANNEL" ]; then UPDATE_CHANNEL="default"; fi
-BUILD_ID=`date +%Y%m%d%H%M%S`
+# Keep the build reproducible by deriving the build ID from SOURCE_DATE_EPOCH
+BUILD_ID=${SOURCE_DATE_EPOCH:-0}
 
 # Paths to Gecko runtimes
 MAC_RUNTIME_PATH="$CALLDIR/xulrunner/Firefox.app"
@@ -644,11 +644,6 @@ if [ $BUILD_MAC == 1 ]; then
 		cp "$MAC_RUNTIME_PATH/../MacOS/XUL" "$CONTENTSDIR/MacOS/"
 	fi
 
-	# Use our own updater, because Mozilla's requires updates signed by Mozilla
-	cd "$CONTENTSDIR/MacOS"
-	check_lfs_file "$CALLDIR/mac/updater.tar.xz"
-	tar xf "$CALLDIR/mac/updater.tar.xz"
-
 	# Modify Info.plist
 	perl -pi -e "s/\{\{VERSION\}\}/$VERSION/" "$CONTENTSDIR/Info.plist"
 	perl -pi -e "s/\{\{VERSION_NUMERIC\}\}/$VERSION_NUMERIC/" "$CONTENTSDIR/Info.plist"
@@ -1027,11 +1022,6 @@ if [ $BUILD_LINUX == 1 ]; then
 		# Copy Ubuntu launcher files
 		cp "$CALLDIR/linux/zotero.desktop" "$APPDIR"
 		cp "$CALLDIR/linux/set_launcher_icon" "$APPDIR"
-		
-		# Use our own updater, because Mozilla's requires updates signed by Mozilla
-		check_lfs_file "$CALLDIR/linux/updater.tar.xz"
-		tar xf "$CALLDIR/linux/updater.tar.xz" --to-stdout updater-$arch > "$APPDIR/updater"
-		chmod 755 "$APPDIR/updater"
 
 		# Copy app files
 		rsync -a "$base_dir/" "$APPDIR/"