diff --git a/test/test_helper.rb b/test/test_helper.rb
index 61581475..04712bee 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -29,14 +29,22 @@
 RubySaml::Logging.logger = TEST_LOGGER
 
 class Minitest::Test
-  def jruby?
+  def self.jruby?
     defined?(RUBY_ENGINE) && RUBY_ENGINE == 'jruby'
   end
 
-  def truffleruby?
+  def jruby?
+    self.class.jruby?
+  end
+
+  def self.truffleruby?
     defined?(RUBY_ENGINE) && RUBY_ENGINE == 'truffleruby'
   end
 
+  def truffleruby?
+    self.class.truffleruby?
+  end
+
   def fixture(document, base64 = true)
     response = Dir.glob(File.join(File.dirname(__FILE__), "responses", "#{document}*")).first
     if base64 && response =~ /\.xml$/
@@ -488,3 +496,19 @@ def encrypt_xml(assertion_xml, private_key)
     encrypted_assertion_xml
   end
 end
+
+# Remove after https://github.com/jruby/jruby/issues/6613 is fixed
+if Minitest::Test.jruby?
+  module JRubyZlibTestExtension
+    @@jruby_zlib_failures = 0
+
+    def run
+      super
+    rescue Zlib::BufError => e
+      raise e unless (@@jruby_zlib_failures += 1) < 10
+      skip "Skipping Zlib::BufError in JRuby, see https://github.com/jruby/jruby/issues/6613"
+    end
+  end
+
+  Minitest::Test.prepend(JRubyZlibTestExtension)
+end