diff --git a/dockerfile b/dockerfile
index 5929c5a..99984d9 100644
--- a/dockerfile
+++ b/dockerfile
@@ -21,6 +21,7 @@ RUN apt-get install -y \
     libmcrypt-dev \
     libreadline-dev \
     libfreetype6-dev \
+    oniguruma-dev \
     g++
 
 # 2. apache configs + document root