diff --git a/travis_config.rb b/travis_config.rb
index c2c6e0c6a9..5904d6880f 100644
--- a/travis_config.rb
+++ b/travis_config.rb
@@ -6,7 +6,7 @@
   conf.gembox 'full-core'
   conf.cc.flags += %w(-Werror=declaration-after-statement)
   conf.compilers.each do |c|
-    c.defines += %w(MRB_GC_STRESS MRB_GC_FIXED_ARENA)
+    c.defines += %w(MRB_GC_STRESS MRB_GC_FIXED_ARENA MRB_METHOD_CACHE)
   end
 
   build_mrbc_exec