Untrimmed content with single quote shows trimmed suffix

I was using Smart Trim to trim a certain field to 100 characters, but then I noticed that one of my data entries was getting trimmed even though it was only 80 characters long. I looked into the module, and discovered that the untrimmed text had an encoded single quote in the content, and the trimmed text had decoded the quote, which shortened the content, causing the suffix to appear.

I did some digging, and found that $output2 is put through _filter_htmlcorrector(), but $output isn't before the length check. In my environment, I also put $output through that function, and it solved my problem, but I didn't go through the code enough to know if that's the best possible solution.