diff --git a/test/ruby/test_gc.rb b/test/ruby/test_gc.rb
index 401af99f3b..a2ccc63218 100644
--- a/test/ruby/test_gc.rb
+++ b/test/ruby/test_gc.rb
@@ -145,6 +145,7 @@ class TestGc < Test::Unit::TestCase
     assert_equal :newobj, GC.latest_gc_info[:gc_by]
     eom
 
+    GC.start
     GC.start
     assert_equal :force, GC.latest_gc_info[:major_by] if use_rgengc?
     assert_equal :method, GC.latest_gc_info[:gc_by]