diff --git a/Dockerfile b/Dockerfile
index fad8c68..3ab2340 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -21,6 +21,7 @@ RUN apk add --no-cache \
 
 # Install PHP modules
 RUN apk add --no-cache --virtual .build-deps \
+        icu-dev \
         libzip-dev \
         freetype-dev \
         libpng-dev \