diff --git a/cmd/fluentd/fluent-plugin-grafana-loki.gemspec b/cmd/fluentd/fluent-plugin-grafana-loki.gemspec
index fbcdf842a6976..241aeb15fa322 100644
--- a/cmd/fluentd/fluent-plugin-grafana-loki.gemspec
+++ b/cmd/fluentd/fluent-plugin-grafana-loki.gemspec
@@ -25,7 +25,7 @@ Gem::Specification.new do |spec|
   # spec.test_files    = test_files
   # spec.require_paths = ['lib']
 
-  spec.add_dependency 'fluentd', '1.9.3'
+  spec.add_dependency 'fluentd', ['>=1.9.3', '< 2']
 
   spec.add_development_dependency 'bundler'
   spec.add_development_dependency 'rake', '~> 12.0'