diff --git a/install/docker/Dockerfile.s6 b/install/docker/Dockerfile.s6
index be8ff91bb2..f0d0db008c 100644
--- a/install/docker/Dockerfile.s6
+++ b/install/docker/Dockerfile.s6
@@ -15,10 +15,11 @@ COPY fs /
 ARG S6_OVERLAY_VERSION=3.1.1.2
 ENV S6_CMD_WAIT_FOR_SERVICES_MAXTIME=0
 ENV S6_KEEP_ENV=1
-RUN case "$(uname -m)" in \
-    x86_64) S6_ARCH='x86_64';; \
-    armv7l) S6_ARCH='armhf';; \
-    aarch64) S6_ARCH='aarch64';; \
+ARG TARGETARCH
+RUN case "${TARGETARCH}" in \
+    x86_64) S6_ARCH='amd64';; \
+    armv7l) S6_ARCH='arm';; \
+    aarch64) S6_ARCH='arm64';; \
     *) echo "Your system architecture isn't supported."; exit 1 ;; \
     esac \
   && cd /tmp \