Parse error: syntax error, unexpected '['

Hi,

I am getting the following error message after updating the theme:

Parse error: syntax error, unexpected ‘[‘ in /www/htdocs/xxx/wp-content/themes/xxx/functions.php on line 15

Line 15, 16 and 17 of the theme functions.php are:

wp_enqueue_style('magazine-body-font', '//fonts.googleapis.com/css?family='.str_replace(" ", "+", of_get_option('magazine_posttext')['face']).':100,300,400,700' );

wp_enqueue_style('magazine-title-font', '//fonts.googleapis.com/css?family='.str_replace(" ", "+", of_get_option('google_mixed')['face']).':100,300,400,700' );

wp_enqueue_style('magazine-title-post', '//fonts.googleapis.com/css?family='.str_replace(" ", "+", of_get_option('google_mixed2')['face']).':100,300,400,700' );

I expect this has something to do with the php version on the server which I am not able to change.

Does anyone have a solution? Many thanks for your help!