diff --git a/pg.gemspec b/pg.gemspec
index 310dc354..091fbdf8 100644
--- a/pg.gemspec
+++ b/pg.gemspec
@@ -20,6 +20,9 @@ Gem::Specification.new do |spec|
   spec.metadata["changelog_uri"] = "https://github.com/ged/ruby-pg/blob/master/History.md"
   spec.metadata["documentation_uri"] = "http://deveiate.org/code/pg"
 
+  # https://github.com/oneclick/rubyinstaller2/wiki/For-gem-developers#msys2-library-dependency
+  "msys2_mingw_dependencies" => "postgresql",
+
   # Specify which files should be added to the gem when it is released.
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
   spec.files = Dir.chdir(File.expand_path(__dir__)) do