diff --git a/docker-build.sh b/docker-build.sh
index e5fc363..08083c2 100755
--- a/docker-build.sh
+++ b/docker-build.sh
@@ -2,7 +2,26 @@
 set -euo pipefail
 
 ISEMU=${1:-0}
+if [ "$ISEMU" -ne "1" ] ; then
+  ISEMU="0"
+fi
 
+# clean up build artifacts when switching to/from emulator builds
+if [ "$ISEMU" -eq "1" ] && ! [ -f ./build100/.for_emulators ] ; then
+  rm  -rf  ./build100/
+elif [ "$ISEMU" -eq "0" ] && ! [ -f ./build100/.for_switch ] ; then
+  rm  -rf  ./build100/
+fi
+
+# remember what system this build is for
+mkdir  -p  ./build100/
+if [ "$ISEMU" -eq "1" ] ; then
+  touch  ./build100/.for_emulators
+else
+  touch  ./build100/.for_switch
+fi
+
+# build
 export DOCKER_BUILDKIT=1
 docker  build  .  -t smoo-client-build
 docker  run  --rm       \