diff --git a/pg-ldap-sync.gemspec b/pg-ldap-sync.gemspec
index 8693de8..1cf03c9 100644
--- a/pg-ldap-sync.gemspec
+++ b/pg-ldap-sync.gemspec
@@ -26,7 +26,7 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency "pg", "= 1.2.3"
   spec.add_development_dependency "ruby-ldapserver", "~> 0.7"
   spec.add_development_dependency "minitest", "~> 5.0"
-  spec.add_development_dependency "bundler", ">= 1.16", "< 3.0"
+  spec.add_development_dependency "bundler", "= 1.15.3"
   spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "minitest-hooks", "~> 1.4"
 end