diff --git a/Makefile b/Makefile
index 2e409c1..a4f1431 100644
--- a/Makefile
+++ b/Makefile
@@ -34,7 +34,7 @@ out.apk: AndroidManifest.xml gen/classes.dex $(KEY_PATH)
 	@$(JARSIGNER) -keystore $(KEY_PATH) -storepass '$(KEY_PASS)' $@.tmp $(KEY_NAME)
 	@$(ZIPALIGN) -f 4 $@.tmp $@
 
-	-@mv -f $@.tmp $@
+	-@if [ ! -r "$@" ]; then mv -f $@.tmp $@; fi
 
 gen/classes.dex: prepare $(CLSS)
 	-@echo removing R classes to economy some space