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.