diff --git a/tasks/mruby_build_gem.rake b/tasks/mruby_build_gem.rake
index 896aeb147..9a802097f 100644
--- a/tasks/mruby_build_gem.rake
+++ b/tasks/mruby_build_gem.rake
@@ -106,7 +106,7 @@ module MRuby
           git.run_checkout gemdir, params[:checksum_hash]
         else
           # Jump to the top of the branch
-          git.run_checkout gemdir, branch
+          git.run_checkout gemdir, branch if $pull_gems
         end
       else
         fail "unknown gem option #{params}"