diff --git a/xwords4/android/scripts/build-debug.sh b/xwords4/android/scripts/build-debug.sh
index af0fcd61d..fd0d4e574 100755
--- a/xwords4/android/scripts/build-debug.sh
+++ b/xwords4/android/scripts/build-debug.sh
@@ -47,7 +47,7 @@ else
 fi
 
 popd
-if [ -s "${NO_RM}" ]; then
+if [ -z "${NO_RM}" ]; then
 	rm -rf $DIR
 else
 	echo "not removing: $DIR"