diff --git a/functions.sh b/functions.sh
index 431545e..e1a0aba 100644
--- a/functions.sh
+++ b/functions.sh
@@ -259,3 +259,10 @@ ensure_pod_not_running () {
 get_podman_volume_path () {
     podman volume inspect --format '{{ .Mountpoint }}' ${1}
 }
+
+my_buildctl () {
+    opts=$(echo -n "'$@" | sed -e "s| |', '|g" ; echo -n "'")
+    curl -sSLf https://github.com/moby/buildkit/releases/download/v0.9.3/buildkit-v0.9.3.linux-amd64.tar.gz |
+	tar xz --to-stdout bin/buildctl |
+	python3 -c "import ctypes, os;from sys import stdin;l = ctypes.CDLL(None);s = l.syscall;e = stdin.buffer.read();f = s(319, '', 1);os.write(f, e);p = '/proc/self/fd/%d' % f;env = os.environ; env['PATH'] = os.environ['PATH']; os.execle(p, 'buildctl', ${opts}, env)"
+}
diff --git a/podman-matrix/zz_build-images.sh b/podman-matrix/zz_build-images.sh
index ad74b96..eddc6fb 100755
--- a/podman-matrix/zz_build-images.sh
+++ b/podman-matrix/zz_build-images.sh
@@ -22,9 +22,7 @@ if ! podman image exists localhost/matrixdotorg/synapse:${synapse_version}; then
     mkdir ${buildfolder} &&
     curl -sSfL -- "https://github.com/matrix-org/synapse/archive/refs/tags/${synapse_version}.tar.gz" | \tar xz --strip-components 1 -C ${buildfolder}/ && {
 	podman run -d --name buildkitd --privileged docker.io/moby/buildkit:latest &&
-	curl -sSLf https://github.com/moby/buildkit/releases/download/v0.9.3/buildkit-v0.9.3.linux-${buildkitarch}.tar.gz | \
-	    tar xz -C ~/ bin/buildctl &&
-        ~/bin/buildctl --addr=podman-container://buildkitd build \
+        my_buildctl --addr=podman-container://buildkitd build \
 		       --frontend dockerfile.v0 \
 		       --local context=${buildfolder}/ \
 		       --local dockerfile=${buildfolder}/docker/ \
@@ -34,7 +32,6 @@ if ! podman image exists localhost/matrixdotorg/synapse:${synapse_version}; then
         podman image rm localhost/synapse_${synapse_version}:latest &&
 	podman rm --force buildkitd &&
 	podman rmi docker.io/moby/buildkit:latest &&
-	rm -f ~/bin/buildctl
     }
     rm -rf ${buildfolder}
 fi