diff --git a/test/ruby/test_process.rb b/test/ruby/test_process.rb
index e5ff7cd..0b1c6c0 100644
--- a/test/ruby/test_process.rb
+++ b/test/ruby/test_process.rb
@@ -1585,8 +1585,16 @@ EOS
 
       # test Process.getsid() w/o arg
       assert_equal(Marshal.load(io), Process.getsid)
-      # test Process.setsid return value and Process::getsid(pid)
-      assert_equal(Marshal.load(io), Process.getsid(io.pid))
+
+      if /openbsd/ =~ RUBY_PLATFORM
+        # OpenBSD doesn't allow Process::getsid(pid) when pid is in
+        # different session.
+        refute_equal(Marshal.load(io), Process.getsid)
+      else
+        # test Process.setsid return value and Process::getsid(pid)
+        assert_equal(Marshal.load(io), Process.getsid(io.pid))
+      end
+
       Process.kill(:KILL, io.pid)
     end
   end