diff --git a/dockerfiles/alpine.Dockerfile b/dockerfiles/alpine.Dockerfile
index 5ee094e..8e96f49 100644
--- a/dockerfiles/alpine.Dockerfile
+++ b/dockerfiles/alpine.Dockerfile
@@ -5,6 +5,7 @@ WORKDIR /app
 
 RUN <<EOT
   apk update
+  apk add bash
   gem update --system --no-document
   gem install -N bundler
 EOT