diff --git a/src/gnss.c b/src/gnss.c
index aeb73af..aa1bb6f 100644
--- a/src/gnss.c
+++ b/src/gnss.c
@@ -190,7 +190,7 @@ static void fetch_assistance_data(struct EG25Manager *manager)
     long int size;
 
     /* Fetch assistance data with curl */
-    tmp_file = fdopen(manager->gnss_assistance_fd, "wb");
+    tmp_file = fdopen(manager->gnss_assistance_fd, "wb+");
     url = g_strconcat(manager->gnss_assistance_url, "/",
                       manager->gnss_assistance_file, NULL);
     curl = curl_easy_init();