diff --git a/lib/rbs/environment_loader.rb b/lib/rbs/environment_loader.rb
index de3cb8fa0..f9a393375 100644
--- a/lib/rbs/environment_loader.rb
+++ b/lib/rbs/environment_loader.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+require "pathname" unless defined?(Pathname)
 
 module RBS
   class EnvironmentLoader
diff --git a/lib/rbs/repository.rb b/lib/rbs/repository.rb
index 49285975d..c735aee00 100644
--- a/lib/rbs/repository.rb
+++ b/lib/rbs/repository.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+require "pathname" unless defined?(Pathname)
 
 module RBS
   class Repository