diff --git a/docs/en/installation.md b/docs/en/installation.md
index 87eb6f3d69..00e66f8094 100644
--- a/docs/en/installation.md
+++ b/docs/en/installation.md
@@ -394,6 +394,9 @@ myapp.local {
 # Dockerfile in your project root
 FROM dunglas/frankenphp
 
+# Install required php extension
+RUN install-php-extensions intl
+
 # Copy your CakePHP application
 COPY . /app