Plugin error / deprecated

Hi,

I’m occuring an error pasted below, the plugin is up to date.

Deprecated: strpos(): Non-string needles will be interpreted as strings in the future. Use an explicit chr() call to preserve the current behavior in (…)/public_html/wp-content/plugins/date-time-picker-field/includes/DateTimePicker.php on line 182.
– how I can fix this problem?