diff --git a/lib/qonfig/command_set.rb b/lib/qonfig/command_set.rb
index b3beff7a..7eeb1477 100644
--- a/lib/qonfig/command_set.rb
+++ b/lib/qonfig/command_set.rb
@@ -33,7 +33,7 @@ def add_command(command)
     # @api private
     # @since 0.1.0
     def each(&block)
-      block_given? ? commands.each(&block) : commands.each
+      thread_safe { block_given? ? commands.each(&block) : commands.each }
     end
 
     # @param command_set [Qonfig::CommandSet]