diff --git a/htdocs/core/lib/functions2.lib.php b/htdocs/core/lib/functions2.lib.php
index 9e66d2fdfd0..79659e57750 100644
--- a/htdocs/core/lib/functions2.lib.php
+++ b/htdocs/core/lib/functions2.lib.php
@@ -577,7 +577,7 @@ function isValidVATID($company)
         $vatprefix = $company->country_code;
         if ($vatprefix == 'GR') $vatprefix = '(EL|GR)';
         else $vatprefix = preg_quote($vatprefix, '/');
-        if (! preg_match('/^'.$vatprefix.'[a-zA-Z0-9\-\.]{5,12}$/', str_replace(' ', '', $company->tva_intra)))
+        if (! preg_match('/^'.$vatprefix.'[a-zA-Z0-9\-\.]{5,12}$/i', str_replace(' ', '', $company->tva_intra)))
         {
             return 0;
         }