diff --git a/src/Symfony/Component/Locale/README.md b/src/Symfony/Component/Locale/README.md
index 40c3f2dfb2..7db3d6bf01 100644
--- a/src/Symfony/Component/Locale/README.md
+++ b/src/Symfony/Component/Locale/README.md
@@ -23,10 +23,14 @@ You can run the unit tests with the following command:
 
 If your PHP have the ``intl`` extension enabled but the intl extension ICU data
 version mismatch the one shipped with the component, you can build the data for
-it and use the ``USE_INTL_ICU_DATA_VERSION`` environment variable:
+it and use the ``USE_INTL_ICU_DATA_VERSION`` environment variable.
 
+    php Resources/data/build-data.php
     export USE_INTL_ICU_DATA_VERSION=true
     phpunit
 
+This way the tests will use the ICU data files with the same version of your
+``intl`` extension.
+
 Read the file ``Resources/data/UPDATE.txt`` for more info about building or
 updating the ICU data files.
\ No newline at end of file