diff --git a/mkimg.sh b/mkimg.sh
index 7c6fc94..2581441 100755
--- a/mkimg.sh
+++ b/mkimg.sh
@@ -19,6 +19,10 @@ if [ -z "${ANDROID_PRODUCT_OUT}" ]; then
   exit_with_error "ANDROID_PRODUCT_OUT environment variable is not set. Run lunch first."
 fi
 
+if [ ! -f ${ANDROID_PRODUCT_OUT}/boot.img ] || [ ! -f ${ANDROID_PRODUCT_OUT}/system.img ] || [ ! -f ${ANDROID_PRODUCT_OUT}/vendor.img ]; then
+  exit_with_error "Partition image not found. Run make first."
+fi
+
 VERSION=RaspberryVanillaAOSP15
 DATE=$(date +%Y%m%d)
 TARGET=$(echo ${TARGET_PRODUCT} | sed 's/^aosp_//')