diff --git a/test/ruby/test_gc.rb b/test/ruby/test_gc.rb
index 7650c68eca..640c5c6340 100644
--- a/test/ruby/test_gc.rb
+++ b/test/ruby/test_gc.rb
@@ -262,6 +262,9 @@ class TestGc < Test::Unit::TestCase
       objects.append(100.times.map { '*' })
     end
 
+    # We need to ensure that no GC gets ran before the call to GC.start since
+    # it would trigger a major GC. Assertions could allocate objects and
+    # trigger a GC so we don't run assertions until we perform the major GC.
     need_major_by = GC.latest_gc_info(:need_major_by)
     GC.start(full_mark: false) # should be upgraded to major
     major_by = GC.latest_gc_info(:major_by)