diff --git a/assets/lambda/Dockerfile b/assets/lambda/Dockerfile
index 9cb03c1e..6cf6fe9e 100644
--- a/assets/lambda/Dockerfile
+++ b/assets/lambda/Dockerfile
@@ -22,19 +22,21 @@
 
 FROM public.ecr.aws/lambda/ruby:3.2
 
-RUN yum update -y
-RUN yum install -y make automake gcc gcc-c++ kernel-devel \
-  gcc readline-devel libicu-devel zlib-devel \
-  openssl-devel openssl \
-  wget tar gzip \
-  libyaml libyaml-devel \
-  git
+RUN yum update -y \
+  && yum install -y \
+    make automake gcc gcc-c++ kernel-devel \
+    gcc readline-devel libicu-devel zlib-devel \
+    openssl-devel openssl \
+    wget tar gzip \
+    libyaml libyaml-devel \
+    git \
+  && yum clean all
 
 COPY install-pgsql.sh /tmp
 RUN /bin/bash /tmp/install-pgsql.sh
 
 COPY Gemfile ${LAMBDA_TASK_ROOT}/
-RUN gem install bundler && bundle install --gemfile=${LAMBDA_TASK_ROOT}/Gemfile
+RUN gem install bundler:2.15.18 && bundle install "--gemfile=${LAMBDA_TASK_ROOT}/Gemfile"
 
 COPY swarm/ /swarm