diff --git a/Dockerfile b/Dockerfile
index 17c7a1ac..7dc69d22 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,23 +1,30 @@
-FROM ubuntu:focal
+FROM ubuntu:mantic-20231011
 
 WORKDIR /app
 COPY . /app
 
 # installing all system dependencies, yq, ruby-build and rbenv
 RUN apt-get update && \
-    apt-get install --yes --no-install-recommends uuid-runtime curl ca-certificates git make build-essential libssl-dev libreadline-dev zlib1g-dev && \
-    rm -rf /var/lib/apt/lists/* && \
-    curl -L https://github.com/mikefarah/yq/releases/download/v4.24.2/yq_linux_amd64.tar.gz | tar -xzvf - && mv yq_linux_amd64 /usr/bin/yq && \
-    git clone https://github.com/rbenv/rbenv.git ~/.rbenv && \
-    curl -L https://github.com/sstephenson/ruby-build/archive/v20220324.tar.gz | tar -zxvf - -C /tmp/ && \
-    cd /tmp/ruby-build-* && ./install.sh
+    apt-get install --yes --no-install-recommends \
+    uuid-runtime curl ca-certificates git make build-essential \
+    libssl-dev libreadline-dev zlib1g-dev && \
+    rm -rf /var/lib/apt/lists/*
+RUN curl -L https://github.com/mikefarah/yq/releases/download/v4.40.2/yq_linux_amd64.tar.gz | tar -xzvf - && \
+    mv yq_linux_amd64 /usr/bin/yq
+RUN git clone https://github.com/rbenv/rbenv.git ~/.rbenv && \
+    curl -L https://github.com/sstephenson/ruby-build/archive/v20231114.tar.gz | tar -zxvf - -C /tmp/ && \
+    cd /tmp/ruby-build-* && \
+    ./install.sh
 
 # set the env
 ENV PATH /root/.rbenv/bin:/root/.rbenv/shims:$PATH
 RUN echo 'eval "$(rbenv init -)"' >> .bashrc
-RUN echo 'eval "$(rbenv init -)"' >> /etc/profile.d/rbenv.sh # or /etc/profile
+RUN echo 'eval "$(rbenv init -)"' >> /etc/profile.d/rbenv.sh
 
 # run the make file to install the app
-RUN make install
+# override CFLAGS because -w (warning suppression) screws up ruby-build in newer versions
+# when compiling ruby 2.6.x, *but* we need newer ruby-build to compile older openssl
+# on newer Ubuntu releases
+RUN make install RUBY_CFLAGS=''
 
 CMD ["/bin/bash", "script/run_in_docker.sh"]
diff --git a/Gemfile.lock b/Gemfile.lock
index 62d5c72a..7fbc9ba4 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -204,6 +204,7 @@ PLATFORMS
   universal-java-11
   x86-mingw32
   x86_64-darwin-20
+  x86_64-linux
 
 DEPENDENCIES
   activesupport (~> 6.1.7.3)
diff --git a/Makefile b/Makefile
index 65aa34fc..623b1ed7 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,5 @@
 YQ ?= "yq"
+RUBY_CFLAGS ?= -w
 .phony: test ftest lint autocorrect update_config autocorrect-unsafe install build-docker run-docker exec_app tag exec_cli
 .phony: build_utility build_service release_utility_dev release_service_dev release_utility release_service build_utility_gem build_service_gem
 
@@ -67,7 +68,7 @@ push_gem:
 	bundle _$(shell cat .bundler-version)_ exec gem push .gems/*
 
 install:
-	RUBY_CFLAGS="-w" rbenv install -s
+	RUBY_CFLAGS="$(RUBY_CFLAGS)" rbenv install -s
 	- gem install bundler -v $(shell cat .bundler-version) && rbenv rehash
 	bundle _$(shell cat .bundler-version)_ install --jobs 1