diff --git a/Dockerfile b/Dockerfile
index e508dd3..a722ddf 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,6 @@
 # This image builds Yocto jobs using the kas tool
 
-FROM debian:stretch-slim
+FROM debian:buster-slim
 
 ENV DEBIAN_FRONTEND=noninteractive
 
diff --git a/Dockerfile.isar b/Dockerfile.isar
index 5b490dc..6b325f3 100644
--- a/Dockerfile.isar
+++ b/Dockerfile.isar
@@ -3,9 +3,7 @@
 FROM kasproject/kas:latest
 
 ENV LC_ALL=en_US.UTF-8
-RUN echo 'deb http://deb.debian.org/debian buster main' > /etc/apt/sources.list.d/buster.list && \
-    echo "Package: qemu-user-static binfmt-support\nPin: release n=buster\nPin-Priority: 501\n\nPackage: *\nPin: release n=buster\nPin-Priority: -1" > /etc/apt/preferences.d/qemu-user-static && \
-    apt-get update && \
+RUN apt-get update && \
     apt-get install -y -f --no-install-recommends \
             autoconf automake gdisk libtool bash-completion \
             sudo grub2 grub-efi-amd64-bin grub-efi-ia32-bin \