diff --git a/update-base-files.sh b/update-base-files.sh
index 1eb6b51..bb99d22 100755
--- a/update-base-files.sh
+++ b/update-base-files.sh
@@ -1,11 +1,11 @@
 #!/bin/bash
 
-if [ ! -d hardware/interfaces ] ; then
+if [ ! -d $ANDROID_BUILD_TOP/hardware/interfaces ] ; then
   echo "Where is hardware/interfaces?";
   exit 1;
 fi
 
-if [ ! -d system/libhidl/transport ] ; then
+if [ ! -d $ANDROID_BUILD_TOP/system/libhidl/transport ] ; then
   echo "Where is system/libhidl/transport?";
   exit 1;
 fi
@@ -20,24 +20,24 @@
 
 # hardware/libhardware
 hidl-gen $options \
-         -o hardware/libhardware/include/hardware/sensors-base.h \
+         -o $ANDROID_BUILD_TOP/hardware/libhardware/include/hardware/sensors-base.h \
          android.hardware.sensors@1.0
 hidl-gen $options \
-         -o hardware/libhardware/include/hardware/nfc-base.h \
+         -o $ANDROID_BUILD_TOP/hardware/libhardware/include/hardware/nfc-base.h \
          android.hardware.nfc@1.0
 hidl-gen $options \
-         -o hardware/libhardware/include/hardware/gnss-base.h \
+         -o $ANDROID_BUILD_TOP/hardware/libhardware/include/hardware/gnss-base.h \
          android.hardware.gnss@1.0
 
 # system/core
 hidl-gen $options \
-         -o system/core/include/system/graphics-base.h \
+         -o $ANDROID_BUILD_TOP/system/core/include/system/graphics-base.h \
          android.hardware.graphics.common@1.0
 
 # system/media
 hidl-gen $options \
-         -o system/media/audio/include/system/audio-base.h \
+         -o $ANDROID_BUILD_TOP/system/media/audio/include/system/audio-base.h \
          android.hardware.audio.common@2.0
 hidl-gen $options \
-         -o system/media/audio/include/system/audio_effect-base.h \
+         -o $ANDROID_BUILD_TOP/system/media/audio/include/system/audio_effect-base.h \
          android.hardware.audio.effect@2.0