diff --git a/test/ruby/test_regexp.rb b/test/ruby/test_regexp.rb
index 5daf67a436..f11d1fb616 100644
--- a/test/ruby/test_regexp.rb
+++ b/test/ruby/test_regexp.rb
@@ -1677,7 +1677,7 @@ class TestRegexp < Test::Unit::TestCase
   def test_cache_optimization_exponential
     assert_separately([], "#{<<-"begin;"}\n#{<<-'end;'}")
     begin;
-      timeout = EnvUtil.apply_timeout_scale(0.2)
+      timeout = EnvUtil.apply_timeout_scale(2)
       Regexp.timeout = timeout
 
       assert_nil(/^(a*)*$/ =~ "a" * 1000000 + "x")