diff --git a/ldclient-rb.gemspec b/ldclient-rb.gemspec
index 46dac190..8c3cc4b1 100644
--- a/ldclient-rb.gemspec
+++ b/ldclient-rb.gemspec
@@ -34,8 +34,8 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency "json", [">= 1.8", "< 3"]
   spec.add_runtime_dependency "faraday", [">= 0.9", "< 2"]
   spec.add_runtime_dependency "faraday-http-cache", [">= 1.3.0", "< 3"]
+  spec.add_runtime_dependency "net-http-persistent", [">= 2.9", "< 4.0"]
   spec.add_runtime_dependency "semantic", "~> 1.6"
-  spec.add_runtime_dependency "net-http-persistent", "~> 2.9"
   spec.add_runtime_dependency "concurrent-ruby", "~> 1.0"
   spec.add_runtime_dependency "http_tools", '~> 0.4.5'
   spec.add_runtime_dependency "socketry", "~> 0.5.1"