diff --git a/app/Makefile b/app/Makefile
index b142065..7a67323 100644
--- a/app/Makefile
+++ b/app/Makefile
@@ -42,7 +42,7 @@ SHELL=/bin/bash
 	./.Makefile.scripts/make--AppActivity.java.sh > $@
 
 # make the resources "R.java" thing
-./src/package/R.java : $(shell find ./res -type f) app-config.sh ./src/package ./AndroidManifest.xml
+./src/package/R.java : $(shell find ./res -type f) app-config.sh ./src/package ./AndroidManifest.xml ./android-sdk/installed
 	source app-config.sh; $${ANDROID_SDK_ROOT}/$$(tr ';' '/' < android-sdk/.installed.buildtools.version.current)/aapt package \
 	  -v -f -m  -S ./res -J ./src -M ./AndroidManifest.xml \
 	  -I $${ANDROID_SDK_ROOT}/$$(tr ';' '/' < android-sdk/.installed.platforms.version.current)/android.jar