install_with_repo() {
     local APP_NAME=$1
     local REPO_URL="https://$2"
-    local KEY_FILENAME_SOURCE="${3}.gpg"
+    local KEY_FILENAME_SOURCE=${3}
     local SUITE=$4
 
     local TEMP_DIR
     sudo apt install -y "${APP_NAME}-desktop"
 }
 
-install_with_repo mattermost deb.packages.mattermost.com pubkey stable
+install_with_repo mattermost deb.packages.mattermost.com pubkey.gpg stable
 
-install_with_repo signal updates.signal.org/desktop/apt signal-desktop-keyring xenial
+install_with_repo signal updates.signal.org/desktop/apt keys.asc xenial