diff --git a/Dockerfile b/Dockerfile
index 5b63f01..22e0178 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -18,6 +18,7 @@ RUN apk add --no-cache bash \
     php5-mysql \
     php5-mysqli \
     php5-mcrypt \
+    php5-mbstring \
     php5-ctype \
     php5-zlib \
     php5-gd \