diff --git a/xwords4/android/scripts/ndkbuild.sh b/xwords4/android/scripts/ndkbuild.sh
index d0f840723..b4ef80783 100755
--- a/xwords4/android/scripts/ndkbuild.sh
+++ b/xwords4/android/scripts/ndkbuild.sh
@@ -1,6 +1,11 @@
 #!/bin/sh
 
-OLDDIR=$(pwd)
+set -e -u
+
+if [ ! -e build.xml ]; then
+    echo "no build.xml; please run from root of source tree"
+    exit 1
+fi
 
 if [ -z "$NDK_ROOT" ]; then
     echo -n "NDK_ROOT not set... "
@@ -8,9 +13,6 @@ if [ -z "$NDK_ROOT" ]; then
     exit 1
 fi
 
-cd $(dirname $0)/../XWords4
-
 ${NDK_ROOT}/ndk-build $*
 
-cd $OLDDIR
 echo "$0 done"