diff --git a/test/capsicum_test.rb b/test/capsicum_test.rb
index 32427aa..a1d8dd8 100644
--- a/test/capsicum_test.rb
+++ b/test/capsicum_test.rb
@@ -9,6 +9,8 @@ class CapsicumTest < Minitest::Test
   end
 
   def test_1_within_sandbox
+    skip if RUBY_ENGINE == 'jruby' # fork not supported
+
     refute Capsicum.sandboxed?
 
     result = Capsicum.within_sandbox do
@@ -30,6 +32,7 @@ class CapsicumTest < Minitest::Test
   def test_2_capsicum
     refute Capsicum.sandboxed?
     assert Capsicum.enter!
+    assert Capsicum.enter!
     assert Capsicum.sandboxed?
 
     assert_raises(Errno::ECAPMODE) do