In the more general case, it's usually a good idea to put an extra block (pair of curlies) around each included module's code section. This is in order to emulate the extra scope implied when having the code in a separate file. I.e.

...
{
package Foo;
sub bar {print "bar: hello\n"}
}
{
package Bar;
...
}
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Of course, it won't make a difference in this simple case, but with more complex code, subtle bugs due to scoping issues might result without the extra braces.

Also, depending on whether the included code needs to be compiled/run prior to the rest of the script (as a normal use would do), you might need to put the code in a BEGIN {} block...