Using Statamic Partial Variables within Entries Tags?

Trying to use partials in the Statamic CMS to keep some content areas as DRY as possible.

According to the documentation, I can pass variables to a partial like so:

{{ theme:partial src="sidebar" my_count="2" }}

In my partials/sidebar template, I have the following:

{{ my_count }}

{{ entries:listing folder="projects" }}
  I am number {{ my_count }}
{{ /entries:listing }}

However, when the page loads, the variable inside the {{ entries:listing }} tag is not parsed.

2
I am number
I am number
I am number
I am number
I am number

Am I missing a step to get {{ my_count }} to output when called inside the entries tag pair?

NOTE: My ultimate goal is to pass the variable to a parameter, like so:

{{ entries:listing folder="projects" limit="{{ my_count }}" }}
  ...
{{ /entries:listing }}