diff --git a/htdocs/install/check.php b/htdocs/install/check.php
index 14448841217..d3c5cba1290 100644
--- a/htdocs/install/check.php
+++ b/htdocs/install/check.php
@@ -149,11 +149,19 @@ if (!function_exists("easter_date")) {
 if (!function_exists("utf8_encode")) {
 	$langs->load("errors");
 	print '<img src="../theme/eldy/img/warning.png" alt="Error" class="valignmiddle"> '.$langs->trans("ErrorPHPDoesNotSupportUTF8")."<br>\n";
-	// $checksok = 0;		// If ko, just warning. So check must still be 1 (otherwise no way to install)
+	// $checksok = 0; // If ko, just warning. So check must still be 1 (otherwise no way to install)
 } else {
 	print '<img src="../theme/eldy/img/tick.png" alt="Ok" class="valignmiddle"> '.$langs->trans("PHPSupport", "UTF8")."<br>\n";
 }
 
+// Check for mbstring extension
+if (!extension_loaded("mbstring")) {
+	$langs->load("errors");
+	print '<img src="../theme/eldy/img/warning.png" alt="Error" class="valignmiddle"> '.$langs->trans("ErrorPHPDoesNotSupportMbstring")."<br>\n";
+	// $checksok = 0; // If ko, just warning. So check must still be 1 (otherwise no way to install)
+} else {
+	print '<img src="../theme/eldy/img/tick.png" alt="Ok" class="valignmiddle"> '.$langs->trans("PHPSupport", "mbstring")."<br>\n";
+}
 
 // Check if intl methods are supported
 if (empty($_SERVER["SERVER_ADMIN"]) || $_SERVER["SERVER_ADMIN"] != 'doliwamp@localhost') {
diff --git a/htdocs/langs/en_US/install.lang b/htdocs/langs/en_US/install.lang
index c1ffee936d7..989f6aa9793 100644
--- a/htdocs/langs/en_US/install.lang
+++ b/htdocs/langs/en_US/install.lang
@@ -21,6 +21,7 @@ ErrorPHPDoesNotSupportCurl=Your PHP installation does not support Curl.
 ErrorPHPDoesNotSupportCalendar=Your PHP installation does not support php calendar extensions.
 ErrorPHPDoesNotSupportUTF8=Your PHP installation does not support UTF8 functions. Dolibarr cannot work correctly. Resolve this before installing Dolibarr.
 ErrorPHPDoesNotSupportIntl=Your PHP installation does not support Intl functions.
+ErrorPHPDoesNotSupportMbstring=Your PHP installation does not support mbstring functions.
 ErrorPHPDoesNotSupportxDebug=Your PHP installation does not support extend debug functions.
 ErrorPHPDoesNotSupport=Your PHP installation does not support %s functions.
 ErrorDirDoesNotExists=Directory %s does not exist.