diff --git a/appveyor.yml b/appveyor.yml
index b4514ec276..94097e4931 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -35,4 +35,4 @@ install:
 build_script:
   - set YACC=.\win_flex_bison\win_bison.exe
   - set MRUBY_CONFIG=appveyor_config.rb
-  - ruby .\minirake test all
+  - ruby .\minirake test all 2>&1