call_user_function_ex() affects zval value

Hi, I'm working on PHP7 compatibility for an extension (which I didn't write). I discovered an issue with a call like this: call_user_function_ex(EG(function_table), NULL, zval, &retval, 5, params, 0, NULL); When zval refers to a [object, string] array, its value is different after this call. I haven't seen this issue when zval is a string. I realize the context probably matters here, but I'm having trouble narrowing down what could be doing this. Any suggestions on how to debug this? Thanks, Adam