diff --git a/test/support/utils.rb b/test/support/utils.rb
index 8f807599e..779afe9dc 100644
--- a/test/support/utils.rb
+++ b/test/support/utils.rb
@@ -239,9 +239,14 @@ def run_program(env, cmd, input = "")
     #
     def run_byebug(*args, input: "")
       caller_method = Thread.current.backtrace_locations[2].label
-      cmd = [*binstub, "-r", "simplecov", *args]
+      cmd = [*binstub, *args]
+      byebug_dir = File.absolute_path(File.join("..", "..", "lib"), __dir__)
+      env = {
+        "MINITEST_TEST" => caller_method,
+        "RUBYOPT" => "-r simplecov -I #{byebug_dir}"
+      }
 
-      run_program({ "MINITEST_TEST" => caller_method }, cmd, input)
+      run_program(env, cmd, input)
     end
 
     #
@@ -251,8 +256,7 @@ def binstub
       cmd = "exe/byebug"
       return [cmd] unless Gem.win_platform?
 
-      byebug_dir = File.absolute_path(File.join("..", "..", "lib"), __dir__)
-      [RbConfig.ruby, "-I", byebug_dir, cmd]
+      [RbConfig.ruby, cmd]
     end
   end
 end