diff --git a/core/Makefile b/core/Makefile
index 2315923..42eda82 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1327,6 +1327,7 @@
 	@echo "Package OTA: $@"
 	$(hide) MKBOOTIMG=$(BOARD_CUSTOM_MKBOOTIMG) \
 	   ./build/tools/releasetools/ota_from_target_files -v \
+	   --block \
 	   -p $(HOST_OUT) \
 	   -k $(KEY_CERT_PAIR) \
 	   $(BUILT_TARGET_FILES_PACKAGE) $@