diff --git a/tools/test-install/install b/tools/test-install/install
index 3b81296c35..d1f6ffab60 100755
--- a/tools/test-install/install
+++ b/tools/test-install/install
@@ -45,7 +45,7 @@ done
 message="$(cat <<EOF
 
 Container:
-  sudo lxc-attach -n $CONTAINER_NAME
+  sudo lxc-attach --clear-env -n $CONTAINER_NAME
 
 Unpacked tree:
   sudo ls $shared_dir/mnt/zulip-server
@@ -73,7 +73,7 @@ lxc-copy --ephemeral --keepdata -n "$BASE_CONTAINER_NAME" -N "$CONTAINER_NAME" \
 "$THIS_DIR"/lxc-wait -n "$CONTAINER_NAME"
 
 run() {
-    lxc-attach -n "$CONTAINER_NAME" -- "$@"
+    lxc-attach --clear-env -n "$CONTAINER_NAME" -- "$@"
 }
 
 run eatmydata -- /mnt/src/zulip-server/scripts/setup/install --self-signed-cert "${INSTALLER_ARGS[@]}"
diff --git a/tools/test-install/lxc-wait b/tools/test-install/lxc-wait
index 09c3338baa..f836a2ff22 100755
--- a/tools/test-install/lxc-wait
+++ b/tools/test-install/lxc-wait
@@ -29,7 +29,7 @@ fi
 # We poll.
 for _ in {1..60}; do
     echo "lxc-wait: $CONTAINER_NAME: polling for boot..." >&2
-    runlevel="$(lxc-attach -n "$CONTAINER_NAME" -- runlevel 2>/dev/null)" \
+    runlevel="$(lxc-attach --clear-env -n "$CONTAINER_NAME" -- runlevel 2>/dev/null)" \
         || { sleep 1; continue; }
     if [ "$runlevel" != "${0%[0-9]}" ]; then
         echo "lxc-wait: $CONTAINER_NAME: booted!" >&2
diff --git a/tools/test-install/prepare-base b/tools/test-install/prepare-base
index 20643d372d..6b6e9c5b38 100755
--- a/tools/test-install/prepare-base
+++ b/tools/test-install/prepare-base
@@ -34,7 +34,7 @@ lxc-start -n "$CONTAINER_NAME"
 "$THIS_DIR"/lxc-wait -n "$CONTAINER_NAME"
 
 run() {
-    lxc-attach -n "$CONTAINER_NAME" -- "$@"
+    lxc-attach --clear-env -n "$CONTAINER_NAME" -- "$@"
 }
 
 run passwd -d root