warning: Illegal string offset 'value' in /sites/all/modules/cck/modules/number/number.module on line 555

Warning after PHP Update 5.3 --> 5.6

Hi,
after updating PHP from 5.3 to 5.6 I get this error trying to import - on step 7:
warning: Illegal string offset 'value' in /sites/all/modules/cck/modules/number/number.module on line 555

The referred code of line 555 is:

$value = $element['#value'][$field_key];

Can someone help me to adapt this code for PHP 5.6 ?

Thanks in advance!