diff --git a/libheif/file.cc b/libheif/file.cc
index ce04122098a..76fbe89c021 100644
--- a/libheif/file.cc
+++ b/libheif/file.cc
@@ -758,7 +758,7 @@ Error HeifFile::get_compressed_image_data(heif_item_id ID, std::vector<uint8_t>*
 
   if (item_type == "iden") {
     // we want to return the image data for the source image
-    heif_item_id to_ID;
+    heif_item_id to_ID = 0;
     Error error = get_source_image_id(ID, &to_ID);
     if (error.error_code != heif_error_Ok) {
       return error;