Using Template.registerHelper

I'm following the readme to add a registerHelper to break apart my email templates:

Here are the relevant versions:
```
dburles:spacebars-tohtml@1.0.1
blaze@2.3.2
blaze-html-templates@1.1.2
METEOR@1.7.0.3
```

I'm getting an error `Template is not defined`. I'm assuming this is because `Template` is not available on the server.

I've tried putting the `Template.registerHelper` in the `server` folder and the `lib` folder and it results in the same issue.

Any ideas what might be causing this?