diff --git a/package/php/Config.ext b/package/php/Config.ext
index 464937549..241e4a95a 100644
--- a/package/php/Config.ext
+++ b/package/php/Config.ext
@@ -192,6 +192,11 @@ comment "intl support needs a toolchain w/ C++, wchar, threads"
 	depends on BR2_ARCH_HAS_ATOMICS
 	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_USE_WCHAR || !BR2_TOOLCHAIN_HAS_THREADS
 
+config BR2_PACKAGE_PHP_EXT_MBSTRING
+	bool "mbstring"
+	help
+	  multibyte string support
+
 comment "Image processing"
 
 config BR2_PACKAGE_PHP_EXT_EXIF
diff --git a/package/php/php.mk b/package/php/php.mk
index 30c8d02f1..9456f1c9b 100644
--- a/package/php/php.mk
+++ b/package/php/php.mk
@@ -75,6 +75,7 @@ PHP_CONF_OPTS += $(if $(BR2_PACKAGE_PHP_EXT_SOCKETS),--enable-sockets) \
 		$(if $(BR2_PACKAGE_PHP_EXT_CALENDAR),--enable-calendar) \
 		$(if $(BR2_PACKAGE_PHP_EXT_FILEINFO),--enable-fileinfo) \
 		$(if $(BR2_PACKAGE_PHP_EXT_BCMATH),--enable-bcmath) \
+		$(if $(BR2_PACKAGE_PHP_EXT_MBSTRING),--enable-mbstring) \
 		$(if $(BR2_PACKAGE_PHP_EXT_PHAR),--enable-phar)
 
 ifeq ($(BR2_PACKAGE_PHP_EXT_MCRYPT),y)