diff --git a/fluent-plugin-mssql.gemspec b/fluent-plugin-mssql.gemspec
index e553921..88f823e 100644
--- a/fluent-plugin-mssql.gemspec
+++ b/fluent-plugin-mssql.gemspec
@@ -18,6 +18,8 @@ Gem::Specification.new do |spec|
   spec.require_paths = ["lib"]
 
   spec.add_dependency "dbi"
+  spec.add_dependency "dbd-odbc"
+  spec.add_dependency "ruby-odbc"
 
   spec.add_development_dependency "bundler", "~> 1.5"
   spec.add_development_dependency "rake"