diff --git a/inc/class.embed.php b/inc/class.embed.php
index 2e758cd..b2e1a92 100644
--- a/inc/class.embed.php
+++ b/inc/class.embed.php
@@ -122,13 +122,13 @@ private function prepare_atts($atts): array
                 $url = sanitize_text_field($atts['url']);
 
                 // ensure url is sanitized correctly
-                if (str_contains($atts['url'], 'https://cal.com/')) {
+                if (strpos($atts['url'], 'https://cal.com/') !== false) {
                     $url = str_replace('https://cal.com/', '/', $url);
                 }
                 // 'https://' or 'http://' protocol indicate self-hosted instance
-                elseif (str_contains($atts['url'], 'https://') || str_contains($atts['url'], 'http://')) {
+                elseif (strpos($atts['url'], 'https://') !== false || strpos($atts['url'], 'http://') !== false) {
                     // Start searching after 'http(s)://'
-                    $firstSlashPosition = strpos($url, '/', strlen(str_contains($atts['url'], 'https://') ? "https://" : "http://"));
+                    $firstSlashPosition = strpos($url, '/', strlen(strpos($atts['url'], 'https://') !== false ? "https://" : "http://"));
                     $embed_custom_cal_url = substr($url, 0, $firstSlashPosition);
                     $url = substr($url, $firstSlashPosition);
                 }
diff --git a/readme.txt b/readme.txt
index 0fa43e0..5676ab2 100644
--- a/readme.txt
+++ b/readme.txt
@@ -2,9 +2,9 @@
 Contributors: calcom, turn2honey
 Tags: appointment, appointment booking, appointment scheduling, booking calendar, calcom
 Requires at least: 4.0
-Tested up to: 6.0.1
-Stable tag: 1.0.0
-Requires PHP: 5.2.4
+Tested up to: 6.8.2
+Stable tag: 1.0.1
+Requires PHP: 5.6
 License: GNU General Public License
 License URI: https://www.gnu.org/licenses/gpl-3.0.en.html