diff --git a/docker/build/Dockerfile b/docker/build/Dockerfile
index 6ae5cf0a..09fcdbc9 100644
--- a/docker/build/Dockerfile
+++ b/docker/build/Dockerfile
@@ -1,4 +1,4 @@
-FROM ruby:2.4.5-stretch
+FROM ruby:2.5.1-stretch
 ARG USER
 RUN mkdir /myapp
 COPY script/build/debian/prebuild.sh myapp/script/build/debian/prebuild.sh
diff --git a/docker/debug/Dockerfile b/docker/debug/Dockerfile
index c9e5c3c6..f4b95f87 100644
--- a/docker/debug/Dockerfile
+++ b/docker/debug/Dockerfile
@@ -1,4 +1,4 @@
-FROM ruby:2.4.5-stretch
+FROM ruby:2.5.1-stretch
 ARG USER
 RUN mkdir /myapp
 COPY script/build/debian/prebuild.sh myapp/script/build/debian/prebuild.sh