diff --git a/test/fiddle/test_pointer.rb b/test/fiddle/test_pointer.rb
index 54953bcd..1c7bc15c 100644
--- a/test/fiddle/test_pointer.rb
+++ b/test/fiddle/test_pointer.rb
@@ -281,11 +281,11 @@ def test_null?
 
     def test_size
       Pointer.malloc(4, Fiddle::RUBY_FREE) do |ptr|
-        assert_equal 4, ptr.size
+        assert_equal(4, ptr.size)
       end
-      assert_equal 0, Pointer.new(0).size
-      assert_equal 0, Pointer.new(0).ref.size
-      assert_equal -1, (Pointer.new(0) + 1).size
+      assert_equal(0, Pointer.new(0).size)
+      assert_equal(0, Pointer.new(0).ref.size)
+      assert_equal(-1, (Pointer.new(0) + 1).size)
     end
 
     def test_size=