diff --git a/src/libstore/download.cc b/src/libstore/download.cc
index 6e39330e40d90edcd7f52fc7e30e50ff38cde2b2..04a2b325c651a1ffd8a41076b3b22c9297348291 100644
--- a/src/libstore/download.cc
+++ b/src/libstore/download.cc
@@ -157,7 +157,7 @@ struct CurlDownloader : public Downloader
             curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0);
         }
 
-        data->clear();
+        data = make_ref<std::string>();
 
         if (requestHeaders) {
             curl_slist_free_all(requestHeaders);