diff --git a/test/lib/jit_support.rb b/test/lib/jit_support.rb
index 3b0d21094d..d00625278f 100644
--- a/test/lib/jit_support.rb
+++ b/test/lib/jit_support.rb
@@ -33,4 +33,12 @@ module JITSupport
       err.match?(JIT_SUCCESS_PREFIX)
     end
   end
+
+  def remove_mjit_logs(stderr)
+    if RubyVM::MJIT.enabled?
+      stderr.gsub(/^MJIT warning: Skipped to compile unsupported instruction: \w+\n/m, '')
+    else
+      stderr
+    end
+  end
 end
diff --git a/test/test_open3.rb b/test/test_open3.rb
index 6011ddd733..c480b8cef1 100644
--- a/test/test_open3.rb
+++ b/test/test_open3.rb
@@ -2,6 +2,7 @@
 
 require 'test/unit'
 require 'open3'
+require_relative 'lib/jit_support'
 
 class TestOpen3 < Test::Unit::TestCase
   RUBY = EnvUtil.rubybin
@@ -126,7 +127,7 @@ class TestOpen3 < Test::Unit::TestCase
           i.close
           STDERR.reopen(old)
           assert_equal("zo", o.read)
-          assert_equal("ze", r.read)
+          assert_equal("ze", JITSupport.remove_mjit_logs(r.read))
         }
       }
     }