diff --git a/Dockerfile b/Dockerfile
index 06a9c7f..ba7e23c 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -37,6 +37,7 @@ RUN apk --update --no-cache add \
     php7-fileinfo \
     php7-fpm \
     php7-gd \
+    php7-gmp \
     php7-json \
     php7-ldap \
     php7-mbstring \