diff --git a/test/json/test_json_generate.rb b/test/json/test_json_generate.rb
index ab09ba4eeb..1433b693ab 100755
--- a/test/json/test_json_generate.rb
+++ b/test/json/test_json_generate.rb
@@ -218,6 +218,7 @@ EOT
   def test_gc
     bignum_too_long_to_embed_as_string = 1234567890123456789012345
     expect = bignum_too_long_to_embed_as_string.to_s
+    GC.start
     stress, GC.stress = GC.stress, true
 
     timeout(1) do