diff --git a/lib/foreman_bootdisk/engine.rb b/lib/foreman_bootdisk/engine.rb
index b5acd39f..b1b05cbd 100644
--- a/lib/foreman_bootdisk/engine.rb
+++ b/lib/foreman_bootdisk/engine.rb
@@ -69,7 +69,7 @@ class Engine < ::Rails::Engine
         Host::Managed.include ForemanBootdisk::Orchestration::Compute if SETTINGS[:unattended]
         HostsHelper.prepend ForemanBootdisk::HostsHelperExt
         Foreman::Model::Vmware.prepend ForemanBootdisk::ComputeResources::Vmware if Foreman::Model::Vmware.available?
-        ForemanFogProxmox::Proxmox.prepend ForemanBootdisk::ComputeResources::Proxmox if ForemanFogProxmox::Proxmox.available?
+        ForemanFogProxmox::Proxmox.prepend ForemanBootdisk::ComputeResources::Proxmox if defined?(ForemanFogProxmox)
       rescue StandardError => e
         Rails.logger.warn "#{ForemanBootdisk::ENGINE_NAME}: skipping engine hook (#{e})"
       end