2 files changed, 4 insertions, 2 deletions
diff --git a/test/dl/test_base.rb b/test/dl/test_base.rb
index 0642f0ed89..90d44e6c9d 100644
--- a/test/dl/test_base.rb
+++ b/test/dl/test_base.rb
@@ -1,6 +1,7 @@
+# -*- coding: us-ascii -*-
 require 'test/unit'
-require 'dl'
 require_relative '../ruby/envutil'
+EnvUtil.suppress_warning {require 'dl'}
 
 libc_so = libm_so = nil
 
diff --git a/test/dl/test_c_struct_entry.rb b/test/dl/test_c_struct_entry.rb
index a7a0e34644..b2f1f94419 100644
--- a/test/dl/test_c_struct_entry.rb
+++ b/test/dl/test_c_struct_entry.rb
@@ -1,6 +1,7 @@
+# -*- coding: us-ascii -*-
 require_relative 'test_base'
 
-require 'dl/struct'
+EnvUtil.suppress_warning {require 'dl/struct'}
 
 module DL
   class TestCStructEntity < TestBase