diff --git a/lib/prime.gemspec b/lib/prime.gemspec
index 86247649df..c34d6e9544 100644
--- a/lib/prime.gemspec
+++ b/lib/prime.gemspec
@@ -22,4 +22,7 @@ Gem::Specification.new do |spec|
   spec.require_paths = ["lib"]
 
   spec.required_ruby_version = ">= 2.5.0"
+
+  spec.add_dependency "singleton"
+  spec.add_dependency "forwardable"
 end