diff --git a/Dockerfile b/Dockerfile
index 838670f..e690481 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -3,6 +3,10 @@ FROM python:3
 RUN curl -L https://github.com/hadolint/hadolint/releases/download/v2.10.0/hadolint-Linux-x86_64 > /usr/local/bin/hadolint \
     && chmod +x /usr/local/bin/hadolint
 
+RUN apt-get update \
+    && apt-get install --no-install-recommends -y ruby \
+    && rm -rf /var/lib/apt/lists/*
+
 RUN pip install --no-cache-dir pre-commit docker-compose
 
 RUN mkdir -p /data/pre-commit-cache