diff --git a/.travis.yml b/.travis.yml
index 6c365e3ce00..5193b7c2c77 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -68,6 +68,8 @@ matrix:
     env: DB=mariadb
   - php: '7.2'
     env: DB=mariadb
+  - php: '7.3'
+    env: DB=mariadb
   - php: '5.6'
     env: DB=postgresql
   - php: '7.0'
@@ -76,6 +78,8 @@ matrix:
     env: DB=postgresql
   - php: '7.2'
     env: DB=postgresql
+  - php: '7.3'
+    env: DB=postgresql
   - php: nightly
     env: DB=postgresql
 
diff --git a/htdocs/core/lib/functions2.lib.php b/htdocs/core/lib/functions2.lib.php
index 0356ecc8b23..cc6fb31c1de 100644
--- a/htdocs/core/lib/functions2.lib.php
+++ b/htdocs/core/lib/functions2.lib.php
@@ -1347,7 +1347,7 @@ function hexbin($hexa)
     $strLength = dol_strlen($hexa);
     for ($i = 0; $i < $strLength; $i++)
     {
-        $bin .= str_pad(decbin(hexdec($hexa{$i})), 4, '0', STR_PAD_LEFT);
+        $bin .= str_pad(decbin(hexdec($hexa[$i])), 4, '0', STR_PAD_LEFT);
     }
     return $bin;
 }