diff --git a/app/models/fluent_gem.rb b/app/models/fluent_gem.rb
index 09e6cb6..8622962 100644
--- a/app/models/fluent_gem.rb
+++ b/app/models/fluent_gem.rb
@@ -17,8 +17,11 @@ module FluentGem
       #       but long living caching causes mismatch with actual status e.g. user install plugin from console (without fluentd-ui)
       #       So our decision is that cache `gem list` in 3 seconds
       Rails.cache.fetch(LIST_CACHE_KEY, expires_in: 3.seconds) do
+        last_status = $?
         output = `#{gem} list 2>&1`
-        if $? && $?.exitstatus != 0 # NOTE: $? will be nil on CircleCI, so check $? at first
+        # https://github.com/fluent/fluentd-ui/pull/149#issuecomment-71954588
+        # Sometimes, $? wouldn't override with `#{gem} list` but I don't know why..
+        if $? && last_status != $? && $?.exitstatus != 0 # NOTE: $? will be nil on CircleCI, so check $? at first
           raise GemError, "failed command: `#{gem} list` output: #{output}"
         end
         output.lines.to_a