PATH Environment Variable in Custom Python Environment in Visual Studio Altered

I have a custom Python environment set in Visual Studio for ActivePython. However, it doesn't have access to the system PATH variable. When I type this in the Visual Studio Python Interactive:

import os
os.environ['PATH']

I get:

';C:\\Python35\\lib\\site-packages\\pypiwin32_system32'

It is messing up my Python projects. However, when I use a different environment, it displays the full PATH. It also works fine using the environment outside Visual Studio.

How could I have this Python environment have full access to PATH?