diff --git a/dockerfiles/alpine/Dockerfile b/dockerfiles/alpine/Dockerfile
index b2a52f8..1019b44 100644
--- a/dockerfiles/alpine/Dockerfile
+++ b/dockerfiles/alpine/Dockerfile
@@ -11,6 +11,7 @@ RUN set -e; for pkg in $(go list ./...); do \
 	done
 
 FROM ${base_image} AS resource
+RUN apk update && apk upgrade
 RUN apk add --no-cache bash jq git git-daemon openssh make g++ openssl-dev
 RUN git config --global user.email "git@localhost"
 RUN git config --global user.name "git"
diff --git a/dockerfiles/ubuntu/Dockerfile b/dockerfiles/ubuntu/Dockerfile
index 3e6115c..5f3ee50 100644
--- a/dockerfiles/ubuntu/Dockerfile
+++ b/dockerfiles/ubuntu/Dockerfile
@@ -11,7 +11,8 @@ RUN set -e; for pkg in $(go list ./...); do \
 	done
 
 FROM ${base_image} AS resource
-RUN apt-get update && apt-get install -y jq git make g++ libssl-dev openssh-client
+RUN apt update && apt upgrade -y -o Dpkg::Options::="--force-confdef"
+RUN apt update && apt install -y jq git make g++ libssl-dev openssh-client
 RUN git config --global user.email "git@localhost"
 RUN git config --global user.name "git"
 
@@ -37,7 +38,7 @@ ADD test/ /opt/resource-tests
 RUN /opt/resource-tests/all.sh
 
 FROM resource AS integrationtests
-RUN apt-get update && apt-get install -y squid net-tools
+RUN apt update && apt install -y squid net-tools
 ADD test/ /opt/resource-tests/test
 ADD integration-tests /opt/resource-tests/integration-tests
 RUN /opt/resource-tests/integration-tests/integration.sh