diff --git a/lib/synapse/config_generator/haproxy.rb b/lib/synapse/config_generator/haproxy.rb
index a859abad..34b8615e 100644
--- a/lib/synapse/config_generator/haproxy.rb
+++ b/lib/synapse/config_generator/haproxy.rb
@@ -930,6 +930,7 @@ def generate_config(watchers)
         # if watcher_config is changed, trigger restart
         config_diff = HashDiff.diff(@state_cache.config_for_generator(watcher.name), watcher_config)
         if !config_diff.empty?
+          log.info "synapse: restart required because config_for_generator changed. before: #{@state_cache.config_for_generator(watcher.name)}, after: #{watcher_config}"
           @restart_required = true
         end